1884. | The Condylarthra. 797 
coming less as they ascend or descend to the latter. This sculp- 
ture is unparalleled in the class Mammalia, the nearest resem- 
blance being found in the genus Ichthyosaurus among reptiles. 
A weak development of this sculpture is seen in the Ectoconus ditri- 
gonus on the one hand, and the Haploconus lineatus on the other 
(Figs. 1-2 and 10). 
<= 
Fic. 4.—Ectoconus ditrigonus Cope, two-thirds nat. size; Fig. a, maxillary and 
gern ary bones from below, retaining a good deal of the matrix. Fig. 4, last 
ae inferior molars worn by use. Fig. c, three deciduous, with first permanent 
olar, of a young animal. Original. 
A fragmentary skull shows a postglenoid crest, and the robust 
Posttympanic and paroccipital processes united, and leaving the 
meatus auditorius externus widely open below. The os petro- 
sum is small and not inflated. The foramen ovale is not sepa- 
sins Sats of tibia of Ectoconus ditrigonus ; a, head > b, oe sk aye A “y 
thirds erate Mao individual partially represented in Fig. 3- rig > 
fated from the meatus auditorius below. There are a postglenoid 
foramen and a supraglenoid foramen. There is also a well-mark 
mastoid foramen, The mastoid bone is extensively exposed. 
The cranial walls are thick, and there is a strong sagittal crest. 
_ _ ®© cervical vertebrze are much shorter than in Phenacodus, be- 
Ng deeper than long, and wider than deep (Fig. 6). They are 
