OCTODONTIDJE 483 



and two external enamel-folds; the ears are comparatively small ; 



the tail usually of considerable length, and the general f orm some- 

 what Rat-like. The typical ( '. pUorides is somewhat smaller than 

 the Coypu, and is confined to Cuba; it is remarkable for the 

 sub-division of the lobes of the liver into a number of lobules. 

 0. brachyurus and ft prehensilis are also confined to Cuba. In 

 Jamaica the genus is represented by ft melanurus, which is somewhat 

 smaller than a Rabbit, and has no secondary lobulation of the liver. 1 



Avlacodus? — Upper incisors with three deep grooves; molars 

 as in Capromys. Fur very harsh ; tail moderate, sparsely haired ; 

 maims with rudimentary pollex, and small fifth digit; pes with no 

 hallux, and rudimental fifth digit. One species (A. szuinderia/mts), 

 from Western and Southern Africa, which attains a length of nearly 

 2 feet, and dwells in burrows. 



Plagiodon? — Allied to Capromys, but with the enamel-folds of 

 the molars very complex, and forming a kind of zig-zag pattern in 

 those of the upper jaw. Represented only by P. cedium of Hayti 

 and Jamaica. 



Loncheres* and Echinomys. 5 — These genera include small South 

 American species, in most of which flattened lanceolate spikes are 

 mingled with the fur. The majority of the species occur in Guiana 

 and Brazil, but one species of Echinomys has been recorded from 

 Central America. Fossil remains of both genera occur in the 

 cavern-deposits of Brazil. 



Mesomys. 6 — This genus resembles Loncheres externally, but the 

 pollex has a short curved claw, and there are no spines in the fur. 



Dactylomys. 7 — A Brazilian genus presenting the following dis- 

 tinctive features. Ears short ; tail long and scaly ; pollex minute ; 

 third and fourth digits of manus elongated, with short convex nails. 

 Incisors flat ; molars divided into two lobes, each of which has 

 a single enamel -fold. Represented by two species, D. typus and 

 D. amblyonyx, both of which seem to be rare and but little known. 

 In the elongation of some of the digits Dactylomys recalls Chiromys 

 among the Primates. 



( '< rcomys. 8 — This South American genus is usually placed near 

 Cart&rodon, from which it is readily distinguished by the pointed 

 muzzle and the plain incisors. 



1 For description and anatomy of tins species see Dobson, Proc. Zool. Soc. 

 1884, p. 233. 



2 Temminck, Monographies des Mammiftres, vol. i. p. 245 (1827). 



3 Cuvier, Ann. Sci. Nut. ser. 2, vol. vi. p. 347 (1836). Amended. 



4 Illiger, Prodromus Syst. Mamrn. p. 90 (1811). 



5 Desmarest, Xouv. iJict. d'Hi&t. Nat. vol. x. p. 45 (1817). Amended from 

 Echimys. 6 "Wagner, IVieqmann's Archiv, 1845, pt. 2, p. 145. 



7 Geoffroy, Ann. Sci. Nat. ser. 2, vol. x. p. 126 (1838). 



8 F. Cuvier, Mammiferes, 6ine livr. (1S29). 



