VIII TEP OR ARMADIMIE@OS 7 
ios) 
complete the arcade. The premaxillaries are very small, and are 
usually lost in dried skulls. Coupled with these points of likeness 
are some differences. The lower jaw, for instance, has a well- 
marked coronoid process. The pterygoids do not meet in the 
middle line. The teeth are five or four in each half of each jaw. 
There is no trace of a second set. 
A pecuharity of the Sloths is the enormous number of dorsal 
vertebrae. There are twenty-three of these in Choloepus hoffmanni, 
but only fifteen to seventeen in the Three-toed Sloth, Bradypus. 
As in other American Edentates, the acromion joins the coracoid. 
This connexion occurs in both the Two-toed and the Three-toed 
species. The limbs of these creatures are very long, a concomitant 
of an arboreal life. The femur has no third trochanter. The 
genus Bradypus, which by reason of the fact that it has not lost 
the third toe on the manus seems to be more primitive than 
Choloepus, shows another structural feature which does not bear 
out this conclusion. The trapezoid and the os magnum of the carpus 
are united, while in Choloepus they are perfectly distinct bones. 
The intestine has no caecum. 
There are several species of Sloths. Eminently perfect though 
the organisation of the Sloth in relation to its particular sur- 
roundings appears to us, Buffon selected the animal as the very 
type of imperfection in nature. “One more defect,’ he wrote, 
“they could not have existed.” 
Fam. 3. Dasypodidae.— The family Dasypodidae or Arma- 
dillos contains a considerable number of genera.  Tatusia, Toly- 
peutes, Dasypus, Xenurus, Priodon, and Chlamydophorus. They 
have all a more or less rigid covering of bony plates imbedded in 
the skin, which are not in the least comparable with the scales of 
the Manis. Save the Whales, in one or two genera of which 
traces of a dermal armature exist, the Armadillos are unique 
among existing mammals in this particular. The term “ Edentate ” 
is especially inapplicable to the Armadillos; the genus Priodon 
may have more than forty teeth in each jaw; a total of ninety 
was found in one specimen examined by Professor Kiikenthal. 
In the tendency of the teeth to multiply, we have another 
example of a state of affairs which characterises so many Whales. 
Generally, however, seven to nine is the number of teeth in each 
' This name is written ‘‘ Prionodos”” by Gray, which might lead to a confusion 
with the Carnivore Prionodon. 
