Part 2

1895. _Pteromys nitidus_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 490. December, 1895 (Bunguran).

1900. _Petaurista nitidula_ THOMAS, Novitates Zoologicæ, VII, p. 592. December 8, 1900 (Bunguran).

Seven specimens from Bunguran.

SCIURUS PROCERUS sp. nov.

1894. _Sciurus tenuis_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 659. September, 1894 (Bunguran).

1895. _Sciurus tenuis_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 492. December, 1895 (Bunguran).

_Type._--Adult male (skin and skull) No. 104698 U. S. National Museum. Collected on Bunguran Island, North Natunas, July 18, 1900. Original number 574.

_Characters._--Externally similar to _Sciurus tenuis_ though somewhat smaller. Skull very much smaller and relatively broader than in the related species.

_Color._--The color is exactly like that of _Sciurus tenuis_ from Singapore.

_Skull and teeth._--Except that it appears to be broader throughout, relatively to its length, the skull of _Sciurus procerus_ is essentially a miniature of that of _S. tenuis_, as the braincase shows none of the tendency to increased depth characteristic of the Bornean animal. Ratio of rostral depth to distance between middle of interparietal and lower rim of audital bulla, 50. This ratio is 49 in _S. tenuis_.

_Measurements._--External measurements of type: total length 235; head and body 140; tail vertebræ 95; hind foot 35 (33). Average and extremes of four specimens from the type locality: total length 239.5 (235-247); head and body 140; tail vertebræ 99.5 (95-107); hind foot 35.2 (34-36.5); hind foot without claws 32.9 (31.8-34).

Cranial measurements of type: greatest length 34 (38);[17] basal length 28.6 (32); basilar length 26 (29); palatal length 14.6 (16); diastema, 7.6 (8.8); length of nasals 10.4 (11.4); greatest breadth of nasals 4.8 (5.6); interorbital breadth 12 (12.6); zygomatic breadth 20.8 (21); greatest breadth of braincase 17 (17.6); cranial depth from middle of interparietal to lower rim of audital bulla 14 (15); least depth of rostrum 7 (7.2); mandible, 20 (21); maxillary toothrow (alveoli) 6 (7); mandibular toothrow (alveoli), 6 (7).

_Specimens examined._--Six, all from the type locality.

_Remarks._--This species is immediately distinguishable from its allies by its small skull, scarcely larger than that of _Funambulus macclellandi_.

SCIURUS NATUNENSIS (Thomas).

1894. _Sciurus lowi_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 659. September, 1894 (Sirhassen).

1895. _Sciurus lowi natunensis_ THOMAS, Novitates Zoologicæ, II, p. 26. February, 1895 (Revised determination of Sirhassen specimen).

1895. _? Sciurus lowi natunensis_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 491. (Bunguran and Pulo Laut.)

Four specimens from Sirhassen. The average and extreme measurements are as follows: total length 222 (215-229); head and body 135 (133-140); tail vertebræ 86 (82-89); hind foot 33.6 (33-35); hind foot without claw 31.5 (30.5-32).

SCIURUS LINGUNGENSIS sp. nov.

1895. _? Sciurus lowi natunensis_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 491. (Bunguran and Pulo Laut.)

_Type._--Adult male (skin and skull) No. 104693 U. S. National Museum. Collected on Pulo Lingung off southern extremity of Bunguran, North Natuna Islands, June 19, 1900. Original number 494.

_Characters._--Externally similar to _Sciurus natunensis_ (Thomas), but slightly larger (hind foot with claws 36 instead of 33.6). Skull larger than that of _S. natunensis_, the audital bullæ much broader anteriorly.

_Color._--The color is precisely as in _Sciurus natunensis_, and therefore requires no detailed description.

_Skull._--Skull larger than that of _Sciurus natunensis_ (see measurements) but not different in general form. The audital bullæ are, however, readily distinguishable by the much greater development of the anterior inner lobe. In _Sciurus natunensis_ this lobe is so small as scarcely to form any part of the general contour of the bulla. In _S. lingungensis_ it is nearly equal to the anterior outer lobe, together with which it imparts a distinctly triangular outline to the ventral aspect of the bulla.

_Measurements._--External measurements of type: total length 229; head and body 140; tail vertebræ 89; hind foot 36 (33.7); ear from meatus 12; ear from crown 7. A second specimen from the type locality gives precisely the same measurements.

Cranial measurements of type: greatest length 38 (36);[18] basal length 33 (31); basilar length 30 (29); palatal length 17 (16); greatest length of nasals 11 (10); greatest width of both nasals together 5 (5); interorbital breadth 12 (11.4); zygomatic breadth 22.4 (20); mastoid breadth 17 (16.6); depth of braincase at anterior edge of basi-occipital 13.6 (13); mandible 23 (22); maxillary toothrow (alveoli) 6.4 (7); mandibular toothrow (alveoli) 7 (7).

_Specimens examined._--Two, both from the type locality.

_Remarks._--While _Sciurus lingungensis_ is scarcely distinguishable from _S. natunensis_ by external characters alone, size of the skull and form of the audital bullæ are clearly diagnostic. Both species from the Natunas are separated from the Bornean _S. lowi_ Thomas by their well developed ears, and shorter broader rostral portion of skull.

SCIURUS LUTESCENS sp. nov.

1894. _Sciurus notatus_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 659. September, 1894 (part, specimens from Sirhassen).

_Type._--Adult male (skin and skull) No. 104668 U. S. National Museum. Collected on Sirhassen Island, South Natunas, June 3, 1900. Original number 429.

_Characters._--Allied to _Sciurus notatus_, but considerably smaller than the Bornean representative of the species. Colors very pale, the under parts buff or cream-buff (Ridgway, pl. v, nos. 13 and 11) irregularly tinged with gray.

_Color._--Entire dorsal surface of body and tail a fine grizzle of black and cream-buff, the individual hairs black with two or three cream buff rings. On tail the grizzle is less fine than on back, and it shows a faint tendency to resolve itself into obscure cross bands. On sides of body and on head the cream-buff brightens to buff. Cheeks and muzzle buff, scarcely grizzled. Feet slightly yellower than sides, under parts and inner surface of legs pale buff, palest anteriorly and laterally (where it about matches the cream-buff of Ridgway) brightest along median line. Under side of tail dull ochraceous-buff slightly grizzled with black. Pencil not different from rest of tail. Between the colors of sides and belly are the usual longitudinal stripes. The outer of these is about 5 mm. in width, and cream-buff in color. The inner is about twice as wide, and black, but much obscured by a thick sprinkling of bluish gray hairs. Outer surface of ears concolor with neck, inner surface like cheeks. The sprinkling of bluish gray hairs on sides of belly extends irregularly forward to axilla and inner side of front leg, occasionally to throat and chin.

_Skull._--As compared with the Bornean form of _Sciurus notatus_, the skull of _S. lutescens_ is much smaller (greatest length about 45 instead of 50) the rostrum is relatively shorter and broader, and the audital bullæ are less elongate antero-posteriorly. Teeth as in _Sciurus notatus_ except that they are uniformly smaller.

_Measurements._--External measurements of type: total length 355; head and body 177; tail vertebræ, 177; hind foot 45 (41). Average and extremes of six specimens from the type locality: total length 356 (329-375); head and body 186 (177-196); tail vertebræ 170 (152-178); hind foot 43.8 (41-45); hind foot without claws 40.7 (39-42).

Cranial measurements of type: greatest length 45.4 (50.4)[19]; basal length 39 (43); basilar length 36.4 (41); palatal length 20 (23); palatal width between middle molars 6 (6); greatest length of nasals 13 (14.8); greatest width of both nasals together 6.6 (7); interorbital breadth 15.4 (17); mastoid breadth 21 (21); zygomatic breadth 26 (29); depth of braincase at anterior edge of basi-occipital 16 (16.8); mandible 28 (30); maxillary toothrow (alveoli) 8 (9); mandibular toothrow (alveoli) 8 (9).

_Specimens examined._--Seven (one in alcohol), all from the type locality.

_Remarks._--This squirrel is recognizable among the members of the _S. notatus_ group by its light colors, and particularly by the pallor of the under parts. In the latter characteristic it is approached by the form inhabiting Pulo Laut, but with this exception it is unique among the fulvous bellied species. The six specimens show no variation worthy of note.

SCIURUS SERAIÆ sp. nov.

_Type._--Adult male (skin and skull) No. 104660 U. S. National Museum. Collected on Pulo Seraia, South Natuna Islands, May 29, 1900. Original number 415.

_Characters._--Most nearly related to the small, pallid, _Sciurus lutescens_ from Sirhassen Island, but upper parts slightly less pale, and under parts and pale side stripe buff-yellow, the former without admixture of gray.

_Color._--Upper parts as in _Sciurus lutescens_ except that the pale bands on the hairs are more nearly buff than cream-buff. Tail essentially as in _S. lutescens_ but a shade less pale. Under parts buff-yellow darkening irregularly to dull orange-buff. Dark side stripe broad and well defined.

_Skull._--The skull closely agrees with that of _Sciurus lutescens_ in both size and form, though it is perhaps even broader in proportion to its length. Teeth as in _S. lutescens_.

_Measurements._--External measurements of type: total length 368; head and body 197; tail vertebræ 171; hind foot 44 (40). Average and extremes of four specimens from the type locality: total length 347 (323-368); head and body 184 (171-197); tail vertebræ 163 (152-171); hind foot 43.7 (43-45); hind foot without claws 40.1 (39.5-41).

Cranial measurements of type: greatest length 45; basal length 38.6; basilar length 36; zygomatic breadth 26.4; least interorbital breadth 17; mandible 28; maxillary toothrow (alveoli) 8.6; mandibular toothrow (alveoli) 8.6.

_Specimens examined._--Four, all from the type locality.

_Remarks._--As might be expected from the geographic position of the island it inhabits, _Sciurus seraiæ_ differs from the Bornean _S. notatus_ in much the same way as the Sirhassen representative of the group. It is readily distinguishable from the Sirhassen animal by the different color of the under parts. In color _Sciurus seraiæ_ closely resembles _S. abbottii_ of the Tambelan Islands. The latter is, however, a much larger animal, with a longer and relatively narrower skull.

SCIURUS RUTILIVENTRIS sp. nov.

_Type._--Adult male (skin and skull) No. 104658 U. S. National Museum. Collected on Pulo Midei (Low Island), South Natuna Islands, May 24, 1900. Original number 405.

_Characters._--Size slightly greater than that of _Sciurus lutescens_ and _S. seraiæ_, but not equal to that of the Bornean or Bunguran representatives of _S. notatus_. Color above as in _S. seraiæ_. Under parts bright clear orange-rufous.

_Color._--Color exactly as in _Sciurus seraiæ_ except that the pale side stripe is light cream-buff and the under parts are bright orange rufous. Tail without trace of red suffusion.

_Skull and teeth._--The skull and teeth are a trifle larger than in _Sciurus lutescens_ and _S. seraiæ_, but the difference is scarcely a tangible one.

_Measurements._--External measurements of type: Total length 368; head and body 190; tail vertebræ 178; hind foot 45 (41). Average and extremes of seven specimens from the type locality: total length 356 (330-368); head and body 186 (178-190); tail vertebræ 173 (165-184); hind foot 45.5 (43-48); hind foot without claws 42.2 (39.5-45).

_Specimens examined._--Seven, all from the type locality.

_Remarks._--This squirrel is remarkable among the Natuna members of the _S. notatus_ group for the brilliant color of its under parts. In this respect it surpasses all of the related forms with which I am acquainted. The red color is, however, strictly confined to the body, showing no tendency to spread to the tail as in _S. miniatus_ of the Malay Peninsula.

SCIURUS RUBIDIVENTRIS sp. nov.

1894. _Sciurus notatus_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 659. September, 1894 (part, specimens from Bunguran).

1895. _Sciurus notatus_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 491. December, 1895 (part, specimens from Bunguran).

_Type._--Adult female (skin and skull) No. 104671 U. S. National Museum. Collected on Bunguran Island, North Natunas, June 22, 1900. Original number 498.

_Characters._--Size and general appearance both above and below as in the Bornean form of _Sciurus notatus_, but red of under parts brighter, and cheeks and chin distinctly less fulvous than surrounding parts. Skull with broader, deeper braincase than in the Bornean animal.

_Color._--The color so closely resembles that of the Bornean _Sciurus notatus_ that no detailed description is necessary. Under parts ochraceous-rufous, fading to tawny on throat, everywhere lighter and more tinged with red than in the Bornean animal. In the latter the color of the under parts extends forward to lips and also strongly suffuses the cheeks and sides of head which are only a shade browner than the throat and conspicuously more fulvous than top of head and sides of neck. In _Sciurus rubidiventris_ the cheeks and lips are noticeably suffused with gray so that they form a distinct contrast with both throat, top of head and sides of neck.

_Skull._--The skull agrees in general size with that of the Bornean animal, and is therefore much larger than in the three species from the South Natunas. It is distinguishable by greater general breadth and by the depth of the braincase, which perceptibly exceeds that of _S. notatus_.

_Measurements._--External measurements of type: total length 380; head and body 209; tail vertebræ 171; hind foot 49 (44.5). Averages and extremes of seven specimens from the type locality: total length 378 (368-393); head and body 208 (203-222); tail vertebræ 173 (165-184); hind foot 49.3 (48-50); hind foot without claws 45.7 (44.5-47).

Cranial measurements of type: greatest length 52.4 (50.4);[20] basal length 44 (43); basilar length 41 (41); palatal length 23 (23); palatal width between middle molars 6 (6); greatest length of nasals 15 (14.8); greatest width of both nasals together 7.2 (7); interorbital breadth 18.2 (17); mastoid breadth 23 (21); breadth of braincase above roots of zygomata 24 (22); zygomatic breadth 30.4 (29); depth of braincase at anterior edge of basi-occipital 17.8 (16.8); mandible 29 (30); maxillary toothrow (alveoli) 9 (9); mandibular toothrow (alveoli) 9 (9).

_Specimens examined._--Seven, all from the type locality.

_Remarks._--In both size and general color this squirrel more closely resembles the Bornean representative of the group than it does either of the three forms from the South Natunas. Its relationships, however, appear to be rather with the race inhabiting Singapore Island than with any of its near geographic allies, _Sciurus lautensis_ excepted.

SCIURUS LAUTENSIS sp. nov.

1895. _Sciurus notatus_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 491. December, 1895 (part, specimens from Pulo Laut).

_Type._--Adult female (skin and skull) No. 104683 U. S. National Museum. Collected on Pulo Laut, North Natuna Islands, August 6, 1900. Original number 612.

_Characters._--Size slightly less than that of _Sciurus rubidiventris_ and color conspicuously pallid. Upper parts as in _S. lutescens_; lower parts nearly as in _S. seraiæ_ but rather less dull; pale side stripe much less yellow than belly. Skull as in _Sciurus rubidiventris_.

_Color._--Upper parts and tail as in _Sciurus lutescens_. Cheeks faintly washed with ochraceous-buff. Under parts and inner surface of legs bright ochraceous-buff (distinctly more yellow than Ridgway's pl. V, No. 10). Lateral stripes as in _S. lutescens_ (not distinctly yellowish as in _S. seraiæ_), but black band usually less sprinkled with gray. Scarcely a trace of gray in axillary region or on sides of neck.

_Skull._--The skull in all respects closely resembles that of _S. rubidiventris_ except that it is slightly smaller. Its large size and the correspondingly large teeth readily distinguish it from that of the South Natuna species.

_Measurements._--External measurements of type: total length 375; head and body 195; tail vertebræ 180; hind foot 44 (41). Average and extremes of nine specimens from the type locality; total length 363 (355-379); head and body 189 (171-196); tail vertebræ 170 (165-183); hind foot 45 (44-46); hind foot without claws 42 (41-43).

_Specimens examined._--Ten (one in alcohol), all from the type locality.

_Remarks._--Though suggesting two of the small South Natuna squirrels in color, _Sciurus lautensis_ is obviously related to the dark colored Bunguran form, with which it more nearly agrees in size.

SCIURUS NAVIGATOR (Bonhote).

1894. _Sciurus prevostii_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 656. September, 1894 (Sirhassen).

1901. _Sciurus prevostii navigator_ BONHOTE, Ann. and Mag. Nat. Hist., 7th ser., VII, p. 171. February, 1901 (Sirhassen).

Nine specimens, three from Sirhassen Island and six from Pulo Subi.

Those from Pulo Subi, while agreeing with the topotypes in color, appear to average a trifle smaller, though the series is hardly extensive enough to prove that this is constant.

RATUFA SIRHASSENENSIS (Bonhote).

1894. _Sciurus bicolor albiceps_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 659. September, 1894 (Sirhassen).

1900. _Ratufa ephippium sirhassenensis_ BONHOTE, Ann. and Mag. Nat. Hist., 7th ser., V, p. 498. June, 1900 (Sirhassen).

Two specimens, Sirhassen, June 8, 1900.

This species, though related to _Ratufa ephippium_, with which it agrees in color-scheme, is sharply differentiated by its small size and cranial peculiarities. It is in no way closely allied to _Ratufa bunguranensis_ and _R. nanogigas_.

As compared with that of _Ratufa ephippium sandakanensis_ Bonhote, the skull in addition to its small size (greatest length 57 instead of 65) differs in general narrowness, in the relatively greater breadth of the nasal branches of the premaxillaries, and in the form of the audital bullæ. When the skull is held upside down and viewed from behind the bullæ are seen to be narrower than in the Bornean animal and to rise to a much greater height above the surface of the basi-occipital.

RATUFA BUNGURANENSIS (Thomas and Hartert).

1894. _Sciurus bicolor bunguranensis_ THOMAS and HARTERT, Novitates Zoologicæ, I, p. 658. September, 1894 (Bunguran).

1895. _Sciurus bicolor bunguranensis_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 491. December, 1895 (Bunguran).

1900. _Ratufa ephippium bunguranensis_ BONHOTE, Ann. and Mag. Nat. Hist., 7th ser., V, p. 497. June, 1900.

Thirteen specimens from Bunguran, all in various stages of the change from the bleached winter coat to the summer pelage. In the latter there is some color variation, mostly due to the greater or less distinctness of the drab wash overlying the Prouts-brown or 'chocolate' of the upper parts. Not only does the drab vary in amount in different individuals, but on every specimen it is more noticeable when the animal is viewed from in front. The drab wash is of the same character as that in _Ratufa affinis_, though less conspicuous.

As Mr. Thomas has pointed out to me, after examining a specimen of the latter, _Ratufa bunguranensis_ is closely allied to _R. pyrsonota_. Indeed its relationship to the Siamese species is much closer than to the _R. ephippium_ of Borneo. Together with _R. pyrsonota_ the Bunguran giant squirrel differs conspicuously from that of Borneo in its narrow skull, lengthened audital bullæ, dark feet, dark median line on under surface of tail, and entirely brown back. From _R. pyrsonota_, however, it is readily separable by its darker, less ochraceous color both above and below, drab washed back, and by the much less distinct annulation of the hairs of the dorsal surface.

RATUFA NANOGIGAS (Thomas and Hartert).

1895. _Sciurus bicolor nanogigas_ THOMAS and HARTERT, Novitates Zoologicæ, II, p. 491. December, 1895 (Pulo Laut).

1900. _Ratufa ephippium nanogigas_ BONHOTE, Ann. and Mag. Nat. Hist., 7th ser., V, p. 498. June, 1900 (Pulo Laut).

Four specimens, all from Pulo Laut, the type locality.

This strongly characterized dwarf species is allied to _Ratufa pyrsonota_ and _R. bunguranensis_ with which it agrees in color scheme. It is in no way closely related to the large Bornean _R. ephippium_.

RATUFA ANGUSTICEPS sp. nov.

_Type._--Adult male (skin and skull) No. 104646 U. S. National Museum. Collected on Pulo Lingung, off south coast of Bunguran, June 17, 1900. Original number 481.

_Characters._--Externally like _Ratufa anambæ_ and _R. melanopepla_. Skull about equal to that of latter in length, but conspicuously narrower.

_Color._--As the color is precisely like that of _Ratufa anambæ_ and _R. melanopepla_ it requires no description.

_Skull and teeth._--The skull is immediately recognizable by its general narrowness, but particularly in the region of the anterior zygomatic roots. Ratio of lachrymal breadth to greatest length, 39. In the other black backed species it is about 42. Audital bullæ narrower and more elongate than in _R. melanopepla_, and more elevated above level of basi-occipital (when skull is held upside down). Lateral processes of basi-occipital obsolete.

Teeth as in the related species.

_Measurements._--External measurements of type: total length 748; head and body 342; tail vertebræ 406; hind foot 79 (74).

Cranial measurements of type: greatest length 48.6 (70);[21] basal length 57 (59); basilar length 52 (53); diastema 15.6 (16); length of nasals 22 (23.4); breadth of nasals anteriorly 12 (13); breadth of nasals posteriorly 6 (7); interorbital breadth 27 (28); lachrymal breadth 28.4 (31); breadth between tips of postorbital processes 38 (41); zygomatic breadth 41 (44); mastoid breadth 31 (32.6); mandible 40 (41.6); maxillary toothrow (alveoli) 14 (14); mandibular toothrow (alveoli) 14.6 (14.4).

_Specimens examined._--One, the type.

_Remarks._--While this squirrel exactly resembles the other black backed species with untufted ears, so far as external characters are concerned, it seems to be well differentiated in cranial peculiarities. No black backed _Ratufa_ has hitherto been recorded from the Natunas.

RHINOSCIURUS sp.

An immature long-nosed squirrel was taken on Sirhassen Island, June 4, 1900. In the absence of material for comparison I am unable to determine the species. The genus is new to the islands.

ARCTOGALIDIA INORNATA sp. nov.

_Type._--Adult[22] male (skin and skull) No. 104859 U. S. National Museum. Collected on Bunguran Island, North Natunas, June 23, 1900. Original number 502.

_Characters._--Much smaller than _Arctogalidia leucotis_ from the Malay Peninsula or _A. stigmatica_ from Borneo (greatest length of skull about 100 instead of 115) and in color paler than either, the dark dorsal stripes obsolete in adult.