CREODONTA. 
3. Arctocyonid(S^ Gervais.—Posterior superior molars tubercular. (One 
or more posterior inferior molars tubercular in American genera.) Genera 
Arctocyon, and probably the American genera Miacis Cope, {Uintacyon, 
Leicly), and Bidymictis. 
No genus of this suborder has been found in any formation above the 
Eocene either in Europe or America, and all, excepting Miacis^ PatriofeliSj 
and Stypolophus^ are from the Suessonian or Wahsatch beds only; the three 
genera named being from the Bridger. The nearest ally in Miocene beds 
appears to be ]Iy(Enodon, which approaches nearly to Pterodon in its denti¬ 
tion, so that the two have been regarded as identical by some authors. 
If the latter genus resembles the Creodonta in its brain form, it is quite 
distinct from the Miocene genus ; but, on this point, we are not yet in pos¬ 
session of the necessary information. 
AMBLOOTONUS, Cope. 
Sjsteiu. Cat. Vert. Eocene of New Mexico, U. S. Geog. Survs. W. 100th M., 187.5, p. 7. 
The fossil remains which illustrate this genus include the greater part 
of the dentition of one side of the cranium and that of the posterior part 
of the mandible, with a number of bones of the limbs; the teeth are some¬ 
what worn, but not so much so as to prevent determination. 
The superior molars preserved are three in number, which extend pos¬ 
teriori}^ from below the orifice of the foramen infraorhitale exterius. The 
crowns are longitudinal, and consist of a three-lobed exterior blade and an 
inner depressed tubercle. The last molar is longitudinal, and not transverse, 
as in Oxycena. The superior canine is large, and is preceded, with a short 
intervening diastema, by a very large exterior incisor. The last inferior 
molar consists of two cusps and a rudimental heel. Tlie cusps form a short 
carnassial blade. Their number cannot be determined on the penultimate 
molar, but there is a well-developed heel, and the anterior part of the crown 
is wide. The molar which precedes has three principal cusps, the two 
anterior forming together a blade; in the type-species, there are accessory 
tubercles adjacent to the posterior cusps. 
Among the fragments of the limb-bones of A. sinosus some character¬ 
istic features may be noted. Thus the distal extremity of the ulna exhibits 
