1884. | The Creodonta. 349 
cusp is rudimental or wanting, and the tooth approximates more 
or less the quadrituberculate condition. In the latter subsection 
there are three genera. The first of these, Mioclanus Cope, has 
the inferior true molars quadrituberculate and of equal elevation ; 
the first true molar may have an anterior or fifth tubercle, The 
external cusps of the superior true molars are distinct and coni- 
cal. In Triisodon Cope, the inferior true molars only are known, 
These have four cusps with a rudimental anterior fifth, They dif- 
fer from the corresponding cusps in all the other genera in being 
compressed so as to have fore and aft cutting edges. Diacodon 
Cope, is the third genus. Its superior molars are like those of 
Mioclenus, but the two anterior cusps of the lower true molars 
are much elevated, the posterior are rudimental, and there is a 
rudimental fifth in front. 
Mioclznus presents the only truly quadritubercular lower mo- 
lars in the suborder. It is so far known only from the Puerco or 
oldest Eocene of North America. There are nine species known 
Fig. 16, Fig. 17. 
F ic, 16.-— Af; } lenus č 
below, two-thirds natural size. From the Puerco beds of New Mexico. Fig. a, from 
: . len onus Cope, 
and mandibular bones two-thirds natural size; from the Puerco 
Side 2? ,% Superior true molar teeth from below; 4, left mandibular ramus, external 
we inner side; d, from above. From Report U. S. Geol. Survey Terrs., 
So far, which range from the size of a mink (M. minimus) to that 
of a wolf (M. Jerox) in the sizes of their jaws, but in the case of 
M. ferox, of which a good deal of the skeleton is known, the 
, y Was relatively smaller. The species differ in the form of the 
Superior premolar, and in the robustness of their inferior 
The M. turgidus (Fig. 15) represents the type with 
‘bust premolars, and the M. subtrigonus (Fig. 17) those with 
ore compressed premolars. 
