174 GLIRES. 
2. CHELOGENYS. 
Celogenus, Fréd. Cuvier, Ann. du Mus. x. p. 203 (1807). 
Ceelogenys, Illiger, Prod. Syst. Mamm. &c. p. 92 (1811). 
Hardly any genus of Rodents presents more remarkable peculiarities than Celogenys, 
which nevertheless agrees closely with Dasyprocta in general structure. Externally the 
most striking characters are the reflection of the skin of the cheeks beneath the zygomata 
and the presence of five toes on the hind feet. In the skull the zygomata are enormously 
inflated, the anterior two thirds being composed of the maxillary zygomatic. process, 
which is hollowed out below into a great chamber, lined with mucous membrane and 
communicating with the mouth. The use of this very curious structure has never been 
satisfactorily explained. 
Only one widely distributed species of this genus is known to exist; for the dark- and 
light-coloured animals on which Frédéric Cuvier founded his Celogenus subniger and 
C. fulvuus have long since been proved to be mere varieties, and have even been found 
paired together*. The colour of the Paca may therefore be said to vary from pale 
red-brown to dark sooty-brown, marked with numerous white spots; it attains a length 
of about twenty-four inches. 
1. Celogenys paca. 
Mus paca, Linnzus, Syst. Nat. i. p. 81 (1766, ex Marcgrave)’. 
Coelogenus subniger, Fréd. Cuvier, Ann. du Mus. x. p. 206 (1807, descr. orig.)’; Dugés, La Nat. i. 
p. 188°. 
Celogenys paca, Tomes, P. Z. 8. 1861, p. 288*; Frantzius, Arch. f. Naturg. xxxv. 1, p. 273°. 
Tepescuinte, Tepescuintle of Guatemalans and Costa-Ricans. 
Hab. Muxico, Vera Cruz (Dugés*); Guatemata, Coban, Duefias*, Rio Chisoy (Godman 
& Salvin, Mus. Brit.); Costa Rica (Frantzius®); Panama (Viv. Zool. Soc.).—Souru 
AMERICA to Paraguay. 
This widely-spread Neotropical species is found throughout the hotter parts of 
Central America. The Zoological Society have received several living specimens from 
Panama; and in Costa Rica Dr. v. Frantzius says that it inhabits the warmer and low- 
lying parts of the mountain-ranges, where it lives in burrows near the rivers. Its flesh 
is much prized by the Costa-Ricans, to whom it is known by the Mexican name of 
Tepescuintle—iiterally mountain-dog. The Tepeytzcuitli of Hernandez, however, appears 
to have been a beast of prey 7, from which the name has somehow been transferred to 
the Paca’. 
* Of. Rengger, Siugeth. v. Paraguay, p. 252. 
t De Quadr. Nov. Hisp. fol. 7, cap. xxi. 
