244 On the Extinct Dogs of North America. [ March, 
distinguished from Canis proper, only by the presence of an anterior _ 
cutting lobe of the superior sectorial tooth, the character on 
which Dr. Leidy originally proposed it. There are three species _ 
of the genus known to me, the Æ. sevus, Æ. wheelertanus (Cams 
Cope) and a smaller one which I called Æ. hyenoides, The 
character of the superior sectorial tooth above mentioned is as 
much like that of Hyzna as Felis, and the entire sectorial tooth 
in the Æ. hyenoides is much like that of the former genus. It $ 
all three species the premolars are very robust, as though to aid | 
the sectorials in crushing bones, as they do in the hyenas. The 
second metacarpal bone has on its inner surface a rough area of 
insertion, such as is present in the dogs and absent in the hyenas, : 
and which may indicate five digits in the anterior foot, the general 
character of the Canidz, and not as in the Hyzenidz. I nevertheless _ 
suspect that this genus is the ancestor of the Hyænidæ, through | 
the intermediate forms, Ictitherium and Hyznictis. According 
to Gaudry, Ictitherium has the same number of digits as the Cat- 
ide, and the same dental characters as Ælurodon, excepting 1 | 
the absence of the last inferior molar. He shows a successit 
reduction inthe dimet- 
sions of the superior 
true molars in the three 7 
species of Ictitheriut 
followed by the loss 
— the second in Hyen 
re ne acre Cs, T 
Pikermi, Greece. After Gaudry. Gaudry in placing | o] 
former genus in the series of Epimycterous Carnivora nar z 
Viverridæ ; but that division was largely derived from the Hyp% 
mycterous division, to which the Canidæ belong. se 
The 4lurodon wheelerianus Cope (Fig. 11), was abundi 
Nebraska, though originally discovered in New Mex io 
Loup Fork beds. It is a more robust animal than Æ. sevis, 
differs in various details. The skull was of about the same” 
viz., rather shorter, but stouter than that of the Canis (pus. | 
<E. sævus was equally abundant in Nebraska (Fig. 9). With 
Æ. wheelerianus it probably performed the function of as 
ger, devouring the remains of the antelopes and small caste 
the Loup Fork epoch, The Æ. hyencides is a-smalee ME 
cies with some peculiarities of its own, from Southern N 
the 
