OCTODONTIDZ 481 
tion of one species of Echinomys which ranges into Central America. 
Habits mostly terrestrial, but occasionally fossorial or natatorial. 
Subfamily Ctenodactylines. —NMolars semi-rooted ; jugal as in 
Dipodide ; the two inner toes of the hind feet with a horny comb 
and rigid bristles. Ethiopian region. 
Ctenodactylus.1i— Represented only by C. gundi from North 
Africa, on the borders of the Sahara. Has no premolars ; each foot 
has four digits; the hind limbs are rather longer than the fore; the 
ears small; and the tail reduced toa stump. This animal is about 
the size of the Water-Vole, and dwells on rocky ground, its habits 
Fic, 213.—Skull of Hydrocherus capybara (reduced). 
being diurnal. The peculiar comb-like inner toes are employed for 
dressing the fur. 
Pectinator.2—Closely allied to the preceding, but with a minute 
premolar in each jaw ; and a moderately long and bushy tail. One 
species (P. speket), from Somali-land. 
Subfamily Octodontinze.—Molars semi-rooted or rootless, with 
simple enamel-folds ; fur soft. There are some six existing genera, 
including Rat-like species, all of which are South American, except 
Petromys, which is Ethiopian. 
Octodon.2—Upper and lower molars alike ears moderate ; tail 
of medium length and tufted. Vertebre: C7, D12,L7, 84, C 
25. Typically represented by C. cumingi of Chili and Peru, with 
other species from Chili and Bolivia.’ They live in large com- 
munities. 
1 Gray, Spicilegia Zoologica, p. 10 (1830). 
2 Blyth, Journ. As. Soc. Bengal, vol. xxxiv. p. 294 (1855). 
3 Bennett, Proc. Zool. Soc. 1832, p. 46. 
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