864 THE JOHN DAY FAUNA. 



Entoptychus crassiramis Cope. 



Paleontological Bulletin No. 30, p. 3. Proceeds. Am. Philo. Soc, 1878 (1K79), p. Go. Americ.in Nauralist, 



1883, p. 169, fig. 17. 



Plate LXIV; fig. 5. 



This species was originally established on mandibular rami. I find^ 

 in my later collections, rami of this character attached to crania, which en- 

 able me to fix the definition of the species with greater precision than 

 heretofore. 



The skull is about the size of that of E.planifrons, and has a relatively 

 shorter muzzle. The internal orbital walls are rolled inwards at the supra- 

 orbital region so as to meet at a point opposite the posterior border of the 

 orbital space. Opposite the anterior part of the orbit, the ridges are more 

 widely separated, so that the interspace is a narrow wedge-shaped fcssa, 

 opening forwards. There are no temporal ridges, and only a weak sag- 

 ittal crest. There is no preorbital fossa, but the preorbital ala of the 

 maxillary bone is very prominent. Tlie orbital fossa is small and pro.- 

 found, leaving a full depth to the maxillary alveoli. The otic bulla is ovate, 

 and not keeled or flattened. Its size is medium, and its anterior bottle- 

 neck is continuous with the external pterygoid lamina. The meatal tube 

 is elongate, but not so much so as in E. planifrons. The mastoid bone is 

 not distinguished from the bulla by a groove, and it is convex both ver- 

 tically and transversely. It is injured in the specimen superiorly. The 

 superior molars display an external fissure for part of their length. The 

 premolar has the base extended anteroposteriorly more than in any species 

 of the genus. The premaxillo-maxillary suture is exactly halfway between 

 the bases of the incisor and first molar. It is much nearer the first molar 

 in E. planifrons. 



Measurements. 



M. 



Length of craninm from premaxillary to maBtoid, inclusive of both 048 



Length from front of premaxillary to Pra. iv 022 



Length of molar series on base 008 



Length of otic and mastoid bulhe 015 



Width of otic bulla at middle 007 



luterorbital width 006 



AVidth at anterior border of glenoid cavity 017 



D«pthof skull atM. i 015& 



