28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



hypocone was a well-developed cusp and not just a cingular shelf or 

 prominence. The character of the deuterocone on P^ is scarcely more 

 than specific in importance when taken with the many similarities. 

 Resemblances allying Sphenomeryx to Hylomeryx are the very weak 

 or incipient mesostyles ; conical paracone, metacone, and (evidently) 

 hypocone; and weak protoconule which nearly loses its identity in a 

 protoloph. As a consequence, Sphenomeryx is regarded as a synonym 

 of Hylomeryx; however, the single species "S." quadricuspis is re- 

 ported from a later stage of the Uintan and on the basis of small 

 differences noted is retained as a species distinct from H. annectens. 



HYLOMERYX ANNECTENS ^ Peterson, 1919 



Type. — Anterior portion of a skull and lower jaws, CM. No. 2335. 



Horizon and locality. — Uinta B, Red Bluff wash between White 

 and Green Rivers, Uinta County, Utah. 



Discussion. — Hylomeryx annectens is a little larger, particularly 

 in the premolars, than Bunomeryx montanus. P^ in the type speci- 

 men shows a prominent deuterocone much as in B. montanus, but 

 P* as exposed on the right side appears abnormal. The outer wall is 



MEASUREMENTS IN MILLIMETERS OF DENTITION IN TYPE SPECIMEN OF 



Hylomeryx annectens, cm. no. 2335 



Length of upper cheek series, anterior margin of alveolus for P* to 



posterior margin of M* 38.5 



Upper premolar series, anterior margin of alveolus for P^ to posterior 



margin of P* 22.1 



Upper molar series, M*-M^ inclusive 16.5 



P^ anteroposterior diameter : greatest transverse diameter 5.4 : 2.1 



P', anteroposterior diameter : transverse diameter* 5-8 : 4.5 



P*, anteroposterior diameter : transverse diameter 4.8 : 5.1 



M\ anteroposterior diameter : transverse diameter* 5-7 : 6.5 



M^ anteroposterior diameter : transverse diameter 5.7 : 6.9a 



M', anteroposterior diameter : transverse diameter 5.4 : 6.7 



Lower cheek tooth series, anterior margin of alveolus for Pa to pos- 

 terior margin of root portion of M3 37.8a 



Lower molar series, Mi to posterior margin of root portion of Ms. . . . 18.5a 



P4, anteroposterior diameter : greatest transverse diameter 5-9 ^ 3-3 



Ml, anteroposterior diameter : transverse diameter of talonid 5.8 : 3.7 



M2, anteroposterior diameter : transverse diameter of talonid 5.8a: 4.1 



Ms, anteroposterior diameter : transverse diameter of trigonid 7.0a : 4.0 



a. Approximate. 



* Measurements of posterior upper premolars are taken anteroposteriorly across outer por- 

 tion and transversely perpendicular to outer margin. Those of upper molars are taJcen 

 anteroposteriorly perpendicular to anterior margin and transversely across anterior portion 

 of tooth. 



' Illustrated in Peterson, 1919, figs. 8-10, pi. 36, figs. 5-6. 



