Chapter 3

that measured 29 mm. in crown-rump length.

_=Sciurus truei=_ Nelson.--Three specimens (61300-02) of this species collected by A. A. Alcorn on June 19, 1954, 32 mi. SSE Culiac['a]n extend the known range approximately 210 miles south-southeast from Guirocoba, Sonora (Burt, 1938:38), and provide the first record from Sinaloa. Two of the specimens are females and each was pregnant, one with two embryos and the other with three.

Our specimens generally agree in color with _S. truei_, but are larger than typical individuals and in this respect approach _S. sinaloensis_ of southern Sinaloa. Probably _truei_ and _sinaloensis_ both are only subspecies of the more southerly _S. colliaei_. The three nominal species currently constitute the _S. colliaei_ group in which the presence or absence of P3 seems to vary geographically. The tooth frequently is absent in the northern _truei_ and usually present (invariably in the specimens we have examined) in _colliaei_. Only one of our Sinaloan specimens is accompanied by a skull; in it P3 is present on the right side and absent on the left.

External measurements of the male and two females are, respectively: total length, 512, 508, 504; length of tail, 263, 263, 252; length of hind foot, 64, 63, 64; length of ear from notch, 28, 29, 28. Cranial measurements of 61300 (a female) are: greatest length of skull, 56.2; zygomatic breadth, 32.6; interorbital constriction, 17.9; postorbital constriction, 17.9; length of nasals, 17.3; alveolar length of maxillary tooth-row (on side lacking P3), 10.9.

_=Thomomys umbrinus atrovarius=_ J. A. Allen.--Two specimens (85104-05) from the valley of the R['i]o Piaxtla, 1 mi. SE Camino Re['a]l, 400 ft., resemble the description of _atrovarius_ and agree in size, color and most cranial details with a specimen (85744) from 5 mi. NW Mazatl['a]n. The first-mentioned specimens extend the known range of the subspecies some 50 miles northward from Mazatl['a]n (Bailey, 1915:96), and indicate the probable occurrence of the species at lower elevations in other parts of central Sinaloa.

_=Peromyscus merriami goldmani=_ Osgood.--This subspecies has been reported previously only from the type locality, Alamos, Sonora. Eight specimens were collected in Sinaloa by W. L. Cutter in the autumn of 1957 as follows: 6 mi. N, 1-1/2 mi. E El Dorado (75368-72); 2-1/2 mi. N El Fuerte (75365-66); El Fuerte (75367). The first-mentional locality is approximately 200 miles south-south-east of the type locality. All specimens collected by Cutter were taken in lowland areas, supporting remarks by Commissaris (1960) concerning habitat preferences of _P. merriami_ as compared with those of the closely related _P. eremicus_.

Two of three females from northeast of El Dorado were pregnant on November 18 and 19; one carried four embryos (8 mm. in crown-rump length) and the other three (11 mm.).

External and cranial measurements of _P. m. goldmani_ previously were known only for the holotype (Osgood, 1909:252, 267). Measurements of five adults, a male (75370) and four females (75365, 75369, 75371-72) are, respectively, as follows: total length, 204, 225, 215, 214, 210; length of tail, 105, 120, 110, 108, 109; length of hind foot, 21, 23, 23, 22, 22; length of ear from notch, 21, 21, 21, 20, 21; weight in grams, 29, 19, 35 (pregnant), 33, 34 (pregnant); greatest length of skull, 26.6, 26.5, 26.9, 26.5,----; zygomatic breadth, 13.8, 13.9, 14.1, 13.4,----; interorbital constriction, 3.9, 3.8, 4.0, 4.0,----; mastoid breadth, 11.8, 11.9, 11.8, 11.9, 11.5; length of nasals, 10.1, 9.4, 10.0, 10.0,----; length of maxillary tooth-row, 4.5, 4.3, 4.1, 4.1, 4.1.

_=Onychomys torridus yakiensis=_ Merriam.--Only one specimen of this grasshopper mouse has been reported previously from Sinaloa (from the town of Sinaloa by Hollister, 1914:471). Thirteen specimens in the Museum of Natural History better define the range of the species in the state as follows: 12 mi. N Culiac['a]n (67981-82); 6 mi. N, 1-1/2 mi. E El Dorado (75374-80); 2-1/2 mi. N El Fuerte (75373); 1 mi. S Pericos (62118-20). The individuals from northeast of El Dorado extend the known range of the species some 115 miles south-southeast from Sinaloa.

A female taken on November 17, 1957, from 6 mi. N, 1-1/2 mi. E El Dorado carried two embryos that measured 23 mm. in crown-rump length. A female obtained on November 18 at the same place carried four embryos that measured 10 mm.

_=Neotoma albigula melanura=_ Merriam.--Four specimens from northern Sinaloa, two (85379-80) from 3 mi. N, 1 mi. E San Miguel, 350 ft., and two (75386-87) from 2-1/2 mi. N El Fuerte, provide the first records of the species from the state. _N. a. melanura_ has been known previously from adjacent parts of Sonora and Chihuahua (see Hall and Kelson, 1959:687-688). The specimens from northeast of San Miguel were trapped in runways under cholla cactus, in which nests also were found, on a slope above a rocky arroyo.

_=Spilogale pygmaea=_ Thomas.--Two pygmy spotted skunks from 5 mi. NW Mazatl['a]n (85898-99) are the fifth and sixth of the species to be reported (see Van Gelder, 1959:381) and the second and third taken in Sinaloa (the holotype of _pygmaea_ was obtained at Rosario). One of our specimens, an adult male, was shot on the night of January 10, 1961, as it foraged near an old hollow tree in weedy-thorn bush habitat adjacent to the Pacific Ocean. The hollow tree contained the nest of a woodrat. The second, an adult female, was trapped nearby in a commercial rat trap baited with peanut butter and set near a burrow in a forested area having little undergrowth.

The two individuals here reported fit fairly well the description of color pattern given for the species by Van Gelder (_op. cit._: 379), but are larger (considering sex), externally and cranially, than any of the four specimens reported previously. Measurements of the male and female are, respectively: total length, 291, 270; length of tail, 65, 58; length of hind foot, 38, 35; length of ear from notch, 25, 23; weight in grams, 247.0, 190.5; condylobasal length, 46.0, 42.9; occipitonasal length, 45.0, 41.4; zygomatic breadth, 29.0, 27.3; mastoid breadth, 23.9, 22.5; interorbital constriction, 14.3, 13.6; postorbital constriction, 14.8, 14.1; palatilar length, 15.6, 14.6; postpalatal length, 23.2, 22.4; cranial depth, 16.6, 15.2; length of maxillary tooth-row, 14.2, 13.4. Cranial measurements were taken in the manner described by Van Gelder (_op. cit._: 236-237).

LITERATURE CITED

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