688 CLASS XVII. 



This genus has some conformity with Chinchilla, even in the skull; the 

 hullce tympanicw are particularly large ; the skeleton has 1 7 pairs of ribs, 

 the greatest number occurring in this order. Two species are known, both 

 from Chili: Halrocoma Bennettii Waterh. Voy. of H. M. S. Beayle, 

 Mammal. PI. 28, and Hahrocoma Cuvieri, PI. 29. 



Octodon Bennett, DendroUus Meyen. Incisors smooth, 



jnolars ~ , , destitute of roots, with crown oblique, with a fold 

 4 — 4 



of enamel on each side, sinuate internally. Whiskers numerous. 



Ears somewhat large, rounded, somewhat naked. Feet pentadacty- 



lous, the fore feet with poUex very small, resembling an unguiculate 



wart. Claws small, compressed, incurved, hidden by long hair, 



especially in the hind toes. Tail moderate or somewhat long, with 



tip mostly pencilled with long hairs. 



Sp. Octodon cZe^-its Waterh., Sciuriis dcgus Molina, Gmel., Octodon Oumingii 

 Bennett, Dendrohius degus Meten, Nov. Act. Acad. Cces. Leop. Car.xvi. 

 1, pp. 600 — 602, Tab. 44, Bennett Transact, of the Zool. Soc. 11, i, 1836, 

 PI. 16 J — Octodon Bridgesii Waterh. This genus is nearly allied to the 

 preceding, and also lives in Chili. 



Family XXIX. Eriomyina [CJmichiUtdce BE^J^iEiT.) Incisors 



4 — 4 

 smooth. Molars j — j, destitute of roots, composed of narrow 



transverse parallel lamellae. Hind feet longer than fore feet. Tail 

 furnished with long hair. (Clavicles perfect.) 



This small group of South American mammals has been more accurately 

 known and even for the most part discovered only within the last twenty 

 years. 



Eriomys Cretschmae, Lichtenst., mihi. Molar teeth com- 

 posed each of three lamellee. Ears large, somewhat naked. Whis- 

 kers very long. Hind feet tetradactylous. Claws incurved, small, 

 nearly hidden under the hair of toes. Body covered with very soft 

 hair. 



d) Fore feet pentadactylous. Ears large, rounded {Eriomys in stricter 

 sense. Chinchilla Bennett, Waterh.). 



Sp. Eriomys pellionum mihi, 3Iiis laniger Molina, Gm., Chinchilla F. Cuv, 

 and Geoffr. Saint-Hilaire, Mammif. Livr. 64, Bennett Gardens and 

 Menag. of the Zool. Soc. i. (October, 1829,) pp. i — 12; in Chili and Peru. 

 The fur of the Chinchilla had been prized for some years for its fineness, 

 before any thing determinate was known with regard to the animal and its 

 position in the arrangement of mammals. Compare my paper in Bijdragen 



