1884. ] The Creodonta, | 479 
Leidy (Fig. 22). This animal has been found in the White River 
beds of Nebraska. It is <5 
about the size of the 
Mesodectes caniculus. It 
resembles the gray fox 
of North America in the 
rib-like temporal ridges 
of its skull. 
The remarkable genus 
which I have called Es- 
thonyx, is exceptional 
in the family in the large 
development of its sec- 
ond inferior incisors at 
the expense of the oth- 
ers. One or more of 
the superior incisors has 
been supplanted by ‘the 
large development of the 
ene. that remains. The Fic. 22.—Leptictis haydeni Leidy, skull, natural 
Canines are moderately size, from the White FSi La ia 
NIE preinos. yon aes citadina Ta 
lars are 3 (Fig. 23). 
The last premolars of both jaws are more or less like true molars. 
the inferior true molars support two V’s, of which the anterior 
'S the more elevated. A good deal of the skeleton of the Æ. 
burmeisteri Cope, is known. Its distinct scaphoid and lunar 
bones are represented in Fig. 24 44’. It had five digits in the 
Manus. The cervical vertebrz are more robust than the dorsal, 
and the tail is long and large. The characters of this genus ap- 
Proximate it to the true hedgehogs (Erinaceus), and I formerly 
Placed it in the same order. The tritubercular superior molars 
Separate it Widely. Nevertheless I suspect that it stands in ances- 
relation to the Erinaceide. 
l have described five species of this genus, of which two are 
from the Wasatch of New Mexico, two from the corresponding 
mi of Wyoming, and one, Æ. spatularius, from the Wind River 
of Wyoming. E. acutidens, of the Big Horn pay 
“qualing a red fox in the size of the skull. e skeleto 
E burmeisteri shows, however, that, as in other Creodonta, the 
