482 RODENTIA 
Habrocoma..—Lower molars more complex than the upper ; 
ears large ; and fur extremely soft. Two Bolivian species. 
Schizodon.*— One species, inhabiting elevated spots in the 
Southern Andes, and characterised by the enamel-folds of the upper 
molars meeting in the middle line. The external characters are 
much the same as in Ctenomys, but the ears are larger and the claws 
shorter. 
Ctenomys.?—Incisors broad ; molars rootless, with kidney-shaped 
crowns; last molar small and cylindrical; eyes and ears very 
small; claws larger than the toes. Some four species. Fossil 
remains are common in the Pleistocene of Buenos Ayres and the 
cavern-deposits of Brazil. Habits fossorial. 
Spalacopus.*—Represented by two Chilian species, distinguished 
from the preceding genus by the rudimentary ears. These rodents 
store up magazines of food in their burrows. 
Petromys..—The South African P. typicus is closely allied to 
Spalacopus, but differs by its harsh fur, the shortness of the pollex, 
and the somewhat bushy tail. The teeth are semi-rooted, with 
single inner and outer enamel-folds, nearly meeting in the middle. 
Subfamily Eehinomyinze.—Molars semi-rooted or rootless, with 
deep and curved enamel-folds ; fur more or less harsh, frequently 
mixed with spines; tail generally long. One Ethiopian genus, and 
the remaining nine or so Neotropical. Many of the species are 
of large size, some being arboreal and others aquatic. _ 
Myopotamus.6—Incisors very large; molars with two internal 
and two external enamel-folds in the upper, and three internal and 
one external in the lower jaw, last molar the largest ; ears moder- 
ate ; tail about two-thirds the length of the head and body, scaly, 
and sparsely haired; hind feet webbed; five digits. Vertebre : 
C7,D13,L6,8 4,C 25. The well-known Coypu (JZ coypu), the 
only existing representative of this genus, is one of the largest 
living members of the order, and attains a length of about 2 feet. 
It is common in South America, living in burrows near water, and 
feeding on aquatic plants. Fossil remains of the genus occur in the 
caverns of Brazil, as well as in the Tertiaries of Argentina. 
Capromys.'—This genus comprises arboreal forms from the West 
Indies allied to the Coypu, but, according to Dr. G. E. Dobson, 
showing signs of affinity with the Hystricide. The incisors are 
smaller than in the Coypu, and the upper molars hare one internal 
1 Waterhouse, Proc. Zool. Soc. 1837, p. 80. Amended from dracon, 
* Waterhouse, Proc. Zool. Soc. 1841, p. 91. 
° De Blainville, Bull. Soc. Philom. 1826, p. 62. 
+ Wagler, ibid. p. 1219. 
5 Andrew Smith, 8S. African Quart. Journ. vol. ii. p. 2 (1831). 
® Geoffroy, Ann. du Muséum, vol. vi. p. 81 (1805). 
7 Desmarest, J/ém. Soc. d’ Hist. Nat. vol. i. p. 44 (1822). 
