PART I.--QUADRUMANA (Monkeys).

Monkeys are less afflicted with flukes than most animals. The species known to me are _Distoma laciniatum_, found by Brongniart in the pancreas of _Simia maimon_; _D. orbiculare_ and _Amphistoma emarginatum_, from the intestines of _Cebus trivirgatus_; and _Bilharzia hæmatobia_, a single specimen of which I obtained from _Cercopithecus fuliginosus_. The monkeys of the Old World rarely harbor full-grown tapeworms, but Cysticerci are abundant (_Cyst. tenuicollis_, _C. cellulosa_, _C. pileatus_, _C. crispus_). The common hydatid (_Echinococcus polymorphus_) has been found in many of the Simiæ, and by myself in a Madagascar lemur (_L. macaco_). Dr Leidy also obtained three hydatid cysts from a large monkey. On the last day of the year 1857 I obtained some polycephalous hydatids (_Cœnurus lemuris_) from a ring-tailed lemur. They infested the liver, being more abundant in the lungs. They occupied both sides of the chest. Loose and detached specimens also existed in the cavity of the right pleura. Most of those occupying the chest were connected to the pleura, forming vesicular, semi-transparent masses, varying in size from a filbert to a large walnut, many being united in bundles of much larger size. One of these masses is here drawn (1, fig. 54). It consists of four large Cœnuri, their combined pedicles forming a single stalk. A fifth hour-glass-shaped rudimentary Cœnurus is also visible. Every Cœnurus supports a variable number of lobules, each lobe supporting one or more papillæ. Here and there the papillæ resemble chains of beads. No trace of tapeworm heads could be seen, but under a half-inch objective glass, I found some flat papillæ presenting oval depressions at the surface (2, fig. 54). On examining some of the larger papillæ they were found to consist of membranous layers folded one within the other. These were carefully dissected and examined with the aid of needles, when each one showed in the centre a well-formed tapeworm head with four characteristic suckers, and a prominent rostellum supporting a double coronet of hooks, thirty-two of the latter in all (3, fig. 54). The hooks displayed a marked disparity of size and form. Each hook showed conspicuous anterior and posterior root-processes, the larger set of hooks individually measuring about 1/225″ and the smaller 1/330″ in length (4, fig. 54). There were numerous calcareous corpuscles. The interior of each vesicle was filled with a fluid, in which there were no free scolices. On referring to my notes I find that the lemur had arrived in England about four months previously.

Larval cestodes do not appear to be common in the monkeys of the New World (Cebidæ), nevertheless I found several Cysticerci in the liver of _Macacus radiatus_ (Feb. 19th 1857), and a single specimen in the sooty monkey (Dec. 4th 1857). They were wrongly described by me as Cercariæ. The Cebidæ are largely infested with tapeworms (_Tænia megastoma_ and _T. rugosa_). A species of Ligula (_L. reptans_) has likewise been found beneath the skin of _Callithrix sciureus_ and in one of the marmosets (_Hapale melanurus_). Perhaps the most common helminth infesting monkeys is the nematode called _Filaria gracilis_. I have examined specimens from the orang, the capuchin, and the spider monkey. This parasite commonly occupies the abdomen, coiled beneath the peritoneum, or within folds of the mesentery. It sometimes occurs beneath the skin, or within the connective tissue of superficial muscles. The female worm has been known to reach a length of five feet. In 1873 Mr Samuel Smith, of Clifton, sent me five specimens of this worm. From one of the males, which measured twenty inches in length, I procured some spermatozoa, and found their long diameter to average 1/1400″. These corpuscles and other structures, as well as the worm itself, are figured in my ‘Notes on Entozoa’ quoted below. Next in frequency, perhaps, is the whipworm (_Trichocephalus dispar_), which monkeys of all kinds harbor in common with man. Besides these nematodes, _Physaloptera dilatata_ is found in the stomach of American monkeys, and _Ascaris distans_ also (in the large intestine of marmosets more particularly). This Ascaris has also been found in _Cercopithecus fuliginosus_ and in _Simia sabæa_. A small spiroptera is said to infest the walls of the stomach of _Simia maimon_. To Dr Murie I am indebted for a large roundworm (_Ascaris lumbricoides_) taken from the intestine of a chimpanzee (_Troglodytes niger_), and also for a smaller nematode taken from a green mona-monkey (_Cercopithecus_). This I have described and named _Ascaris cuspidata_. From the intestines of a chacma (_Cynocephalus porcarius_) M. Schafhert procured sixteen examples of a small strongyle (_Str. attenuatus_, Leidy).

The singular monkey known as _Tarsius spectrum_ is liable to be attacked by a filaria (_F. lævis_), which is found beneath the skin. At least two species of Echinorhynchus (_E. spirula_ and _E. elegans_) are known to infest monkeys. I have carefully examined and figured _E. elegans_ in the ‘Zoological Society’s Proceedings,’ from specimens supplied to me by Dr Murie. They had been obtained from a pinche monkey (_Hapale œdipus_) from New Granada. I am under the impression that Diesing’s original description of this parasite is the only one that exists. I have gone over his numerous memoirs contributed to the Vienna Academy, but can find nothing beyond the specific characters given in his ‘Systema.’ All the specimens in the Vienna Museum, whence his description is taken, were collected by Natterer. They were procured from the marakina (_Midas rosalia_), from two other true marmosets (_Hapale ursula_ and _H. chrysoleuca_), and from a squirrel monkey or tee-tee (_Callithrix sciureus_). In the monkey which died at the Zoological Society’s Gardens the cause of death was not clearly due to the parasites; nevertheless, the mucous layer of the intestine, to which the entozoa were attached, showed deep conical pits or depressions at the spots where the worms had anchored themselves. During the perfect retraction of the proboscis of this Echinorhynchus the centre is represented by a wide opening which communicates with a cavity beneath. The end of the neck thus forms a sort of collar, or rosette, made up of rays arranged like the spokes of a wheel. When the proboscis is exserted this collar is more or less convex, but it becomes slightly concave when the proboscis is retracted. Diesing recognised twenty-four rays; they probably vary from that number up to twenty-eight, at least I counted twenty-seven in my specimens. During exsertion the proboscis forms a nipple-like projection. According to Diesing it supports three rows of hooks, but I certainly saw four rows. When separately magnified these hooks present very different appearances as to size and contour. These variations I believe to be due to growth. The largest hooks measured about 1/200″ in length.

As regards insect parasites, it is well known that monkeys are largely infested by fleas, but the species have not been much studied. The same may be said of their mites (_Acaridæ_). A species of Pentastoma (_P. tornatum_, Creplin) has been found occupying little cysts of the peritoneum and omentum in _Simia maimon_ and _S. cynomulgus_. Under a synonym (_Linguatula Diesingii_) it has been very fully described by Van Beneden. Another species (_P. subcylindricum_) has been found attached to the lungs and liver of a marmoset (_Hapale chrysopygus_). Dr Leidy found five specimens of _P. euryzonum_ in cysts on the subperitoneal surface of the liver of _Cynocephalus porcarius_. Leuckart believes that Dr George Harley’s _P. polyzonum_ is the adult state of _P. euryzonum_, and that _P. subcylindricum_ is the larva of _P. proboscideum_, found in _Boa constrictor_ and other serpents.

BIBLIOGRAPHY (No. 42).--_Beneden_ (see Van Beneden).--_Cobbold_, “On _Filaria gracilis_ and _Ascaris cuspidata_,” in ‘Zool. Soc. Proc.,’ Feb. 3, 1874, p. 124.--_Idem_, “List of Entozoa, including Pentastomes, obtained from Animals dying at the Menagerie in 1857-60 inclusive,” ‘Proc. Zool. Soc.,’ 1861.--_Idem_, ‘Entozoa,’ p. 119.--_Idem_, “On Parasite-Larvæ (Cœnurus and Echinococcus of the Lemur),” ‘Intell. Observer,’ vol. iii, pp. 86-96.--_Idem_, “Bilharzia from Cercopithecus,” in ‘Synops. of Distomidæ,’ ‘Proc. Linn. Soc.,’ 1860, Zool. Div., pt. v, p. 31, and in “Parasites from Zool. Gardens.,” in ‘Intell. Obs.,’ June, 1862, p. 352.--_Idem_, “On _Echinorh. elegans_,” ‘Proc. Zool. Soc.,’ 1876, in ‘Notes on Entozoa,’ pt. iii, plate xvi, p. 202.--_Creplin_, “On _P. tornatum_,” ‘Troschel’s Arch.,’ 1849, s. 54.--_Idem_, “_F. gracilis_,” in ‘Wiegm. Arch.,’ 1851, s. 270.--_Diesing_, ‘Syst.,’ l. c., s. 611, and in ‘Sitzb. d. k. Akad.,’ 1854, s. 598.--_Harley, G._, in ‘Proc. Zool. Soc.,’ 1857, p. 12.--_Leidy, J._, “On Pentastoma,” ‘Proc. Phil. Acad. Nat. Sci.,’ 1850, p. 97.--_Idem_, ‘Hydatids,’ l. c., 1856, p. 46.--_Idem_, ‘_Strong. atten._,’ l. c., p. 54.--_Leuckart_, ‘Bau und Entwicklungsgeschichte der Pentastomen,’ 1860, “_P. polyzonum_,” ‘Synops.,’ s. 153.--_Molin_, “On _F. gracilis_,” in ‘Sitzungsb. d. k. Akad. d. Wissensch.,’ 1858, Bd. xxviii, s. 376.--_Schneider_, ‘Monag. der Nem.,’ 1866, “_F. gracilis_,” s. 87.--_Smith, S._, “On _F. gracilis_ found in connection with the Great Omentum of a Spider-monkey,” ‘Proc. of Bristol Naturalists’ Soc.,’ vol. i, 1873.--_Van Beneden_, “_Ling. Diesingii_,” in ‘Mém. Acad. Belgique,’ vol. xxiii, ‘Recherches sur l’organisation et le dévélopment des Linguatules, suivies de la description d’une espèce nouvelle provenant d’un Mandrill,’ 1849.