﻿334 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loo 



floridanus is noted in dental design. Number of folds, or crenulations, 

 of the enamel of anterior aspect of first lower premolar varies from 

 one to five in both species. These folds may be deep or appear as slight 

 crenulations. Frequently a different number of enamel folds obtains 

 in each of the two lower premolars of the same animal in either 

 species. 



Sylvilagus brasiliensis has no near relatives outside the /S. jloridanus 

 group. Nelson's unwarranted inclusion of species so remotely related 

 inter se as aquaticus, palustris, and gabbi (=brasiliensis) in the sub- 

 genus Tapeti presents gratuitous complications to the definition and 

 classification of South American rabbits. Characters of Tapeti Gray 

 as given by Nelson (1909, p. 44) exclude, by strict interpretation of 

 certain one or more details, each of the species purportedly described 

 by them. Actually, some alleged superficial resemblances between 

 swamp rabbits and tapitis as noted by Nelson are nonexistent. 



Nelson (1909, p. 44) grouped brasiliensis, palustris, and aquaticus 

 together on the basis of their "proportionately small, thinly haired 

 ears; small short-haired hind feet, and small, sometimes almost obso- 

 lete, tail." Appearance of length of these structures in the dried skin 

 can be misleading. Ear of S. brasiliensis is comparatively thickly 

 haired, especially basally; length of ear when individual measm-ements 

 are compared is proportionately greater than that of either palustris 

 or aquaticus and averages slightly longer than that of Neotropical 

 forms of S. jloridanus. S. aquaticus is not only a comparatively long- 

 tailed species, but its tail is of the cottontail type. Tail of S. palustris 

 is actually short but intermediate in appearance between the cotton- 

 tail type and the tapiti or "buttontail" type. Contrary to Nelson's 

 belief, there is little difference between the species of Sylvilagus in 

 proportional length of hind foot. Hind foot of aquaticus is more 

 sturdily and broadly built than that of either Jloridanus or brasiliensis. 

 Hind foot of S. palustris differs widely in structure from that of any 

 other species of Sylvilagus. The well-produced middle digit of its 

 relatively narrow hind foot tends markedly toward perissodactylism, 

 a condition fu-st noted by Pocock (1925, p. 692). The extremely long, 

 dark claws of both fore and hind feet serve further to distinguish 

 S. palustris from brasiliensis. 



Nelson (loc. cit.) believed that the "coarse, harsh (and usually rather 

 thin) pelage" was distinctive of species he assigned to Tapeti. Pelage 

 of S. palustris is rather coarse but sleek superficially, the under fur, 

 notably on underparts, extremely thick and soft; altogether, a pelage 

 suited to the marshy habitat and aquatic proclivities of S. palustris. 

 Pelage of Tropical Zone races of S. brasiliensis is comparatively thin, 

 dull in appearance, and definitely not of a texture associated with 

 water repulsion. Pelage of Temperate Zone, or paramo, races of 



