496 CUVIER'S CHINCHILLA CHAP. 



to a separate family which will include but the one species, 

 D. branickii. 



Fam. 6. Chinchiliidae. This family, likewise South American, 

 contains three genera, 1 all of which agree in having long limbs, 

 especially the hind-limbs, and a bushy and well-developed tail. 

 The hair is exceedingly soft, hence the commercial value of 

 " chinchilla." 



The genus Chinchilla, containing but a single species, C. lani- 

 ger, is a small and squirrel-like creature, living at considerable 

 heights in the Andes. The eyes, as it is a nocturnal creature, 

 are naturally large ; and so also are the ears. The fore-feet have 

 five toes, the hind-feet only four ; they are furnished with feeble 

 nails. The innermost toe of the hind-foot has a flat and nail-like 

 claw. There are thirteen dorsal vertebrae, and the long tail has 

 more than twenty. The clavicle is well developed, as in the 

 other genera of this family. The large intestine of this animal 

 is extraordinarily long; the proportions of the different regions 

 of the gut are shown by the following measurements : small 

 intestine, 820 mm.; caecum, 125 mm.; large intestine, 1340 

 mm. Such a disproportion between the large intestine and the 

 small, to the advantage of the former, is a very strange fact in 

 the anatomy of this Eodent. 



The genus Lagidium (also called Lagotis), which includes 

 " Cuvier's Chinchilla," is also a mountain dweller. There are 

 several species of this genus, which differs from Chinchilla, 

 by the complete abortion of the thumb and of the great toe. 

 The intestinal proportions are those of Chinchilla. The ears and 

 tail are long. L. cuvieri measures 1-|- feet in length. 



Lagostomus, again, has but one species, L. tricliodactylus. The 

 animal has a tail about half the length of the body. The digits 

 are reduced as compared with Chinchilla, there being but four on 

 the fore- and three on the hind-feet. There are only twelve dorsal 

 vertebrae, and seven ribs reach the sternum. In the skull a dis- 

 tinguishing mark from the last two genera is the separation of 

 the infra-orbital foramen into two by a thin lamella of bone. The 

 large intestine is between one-half and one -third the length 

 of the small intestine, and thus differs much from that of 

 Chinchilla. 



1 An account of the three genera is to be found in Trans. Zool. Soc. i. 1833, 

 p. 35, by Mr. E. T. Bennett. 



