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. PART II (CHEIROPTERA).