LEPUS.—BRADYPUS. 181 
westward and southward of Alabama. Thence it appears to extend along the east coast 
as far as Orizaba and Yucatan, whence there are many specimens in the National Museum 
at Washington. Mr. Allen says that these last differ in no marked degree from examples 
collected in Mississippi and Louisiana; so the species cannot be considered very variable 
in its characters. 
Order VIII. EDENTATA. 
Suborder I. TARDIGRADA. 
The group of so-called Edentate Mammals is made up of such widely distinct and 
dissimilar forms that their natural arrangement is a very difficult undertaking. Iam 
myself by no means convinced that any of the proposed classifications are satisfactory ; 
but in the meantime I will follow that most generally adopted, and recognize two 
suborders, the Tardigrada of Illiger and the Entomophaga of Wagner. Of these the 
first contains only one recent family, eminently characteristic of the Neotropical fauna. 
Fam. I. BRADYPODIDZ. 
1. BRADYPUS. 
Bradypus, Linnezus, Syst. Nat. i. p. 50 (1766). 
Amongst the strangest of the many strange Edentate types are the Sloths, consti- 
tuting the family Bradypodide, and well represented in Central America by both the 
known genera. Of these the Three-toed Sloths, forming the restricted genus Bradypus*, 
may be at once distinguished by the structure of their fore feet, in which the three 
middle fingers are well developed and powerfully armed with long hooked claws. In 
their osteology they present the very exceptional peculiarity of possessing nine cervical 
vertebre ; their skulls are high and narrow, with merely rudimentary intermaxillaries ; 
and the anterior pair of molars are not larger than the rest. 
A considerable number of species of Three-toed Sloths have been described; but 
much uncertainty still exists as to their claims to distinction. A large series of speci- 
mens with carefully authenticated localities is wanted before a definite conclusion can 
be come to on many points; but the material already available seems to me to show 
that many of the supposed species, especially those of the late Dr. Gray, have been 
* Gray confined the name Bradypus to the Brazilian Collared Sloth, B. torquatus, Illiger; while he named 
all the other three-toed species Arctopithecus (P. Z. 8. 1849, p. 65). It is evident, however, that B. tridactylus 
must be regarded as the type of Bradypus, as instituted by Linneus and restricted by Illiger. If B. torquatus 
is considered to deserve generic distinction, it must stand as Scwopus of Peters (Monatsb. Ak. Berl. 1864, p. 678, 
footnote). 
