DASYPROCTID^. 133 



metatarsal portion reminds one of the same part in the limb 

 of the kangaroo, though it is not so disproportionally 

 elongated. At the heel there is a long naked callous 

 sole or pad, before which is a part covered with hair : the 

 toes are three in nund)er, of which the middle is the most 

 elongated : all are furnished with strong hoof-like nails, 

 and with naked pads beneath. The tail is rather short, 

 and covered with grayish brown hairs, of which the 

 longest form a fringe on the upper surface ; it is gene- 

 rally kept retroverted on the back. The incisor teeth 

 are remarkably large and strong. Fig. 84 represents 

 the skeleton and skull of the Pampas viscacha : a, under 

 view of skull ; b, lov\ er jaw ; c, crown of the second 

 molar tooth of the left side of the lower jaw ; ^, crown 

 of the last molar tooth of the right side of the upper 

 jaw. 



Mr. Brookes's paper on the anatomy of this animal 

 was read before the Linn. Soc. in June, 1828, and pub- 

 lished in the Linn. Trans, for the year following. 



Family— DASYPROCTID^. 



A small family of the Histricine section, which may 

 be termed Dasyproctidoi^ next claims our notice. It em- 

 braces tv,o genera, Ccelogenya and Dasyprocta. In 



4—4 



these genera the molars are , rooted, and bear much 



4 — 4 

 resemblance to those of the porcupines ; they are crowned 

 with distinct tubercles, which, wearing down witli use, 

 give place to winding lines of enamel, set in the interior 

 bony cement. 



The genus Ccelogenys includes two, or perhaps three, 

 distinct species of Rodents, termed Facas (a corruption 

 of the word Pag of the Brazilians, or Paig of the natives 

 of Paraguay ; and Pakiri of some of the tribes of 

 Guiana). 



These animals, the pacas, are remarkable for a curious 

 structural peculiarity in the skull, which imparts a sin- 

 gular aspect to their physiognomy. We give a sketch of 



G 3 



