CONDYLAETHRA. 491 



apparently different in form from the deciduous molar of P. primcevus and 

 puercensis, and as the third true molar is in place and worn, the tooth is 

 doubtless one of the permanent series. When the superior molars are dis- 

 covered it may be found that the species belongs to the genus Diacodexis. 

 The third premolar has an elongate principal cusp, whose anterior part is 

 broken off in my specimens. Its heel is short and wide. The heel of the 

 Pm. Ill is short and wide. On the true molars a weak external cingulum. 

 Enamel slightly wrinkled. 



Measurements. 



M. 



Length of posterior four molars 0277 



Length of crown of Pm. iv 0076 



Diameters M.iii I ''"t«'°P'>«*«"°' 0070 



t transverse 0046 



Depth of ramus at Pm. ii 0100 



Depth of ramus at M. ii 0128 



From the Big-Horn Wasatch formation ; J. L. Wortman. 

 Phenacodus zuniensis Cope. 



Paleontological Balletin, No. 33, p. 492. Sept. 30,1881. Proceeds. Amer. Philo. Soc, 1881, p. 492. 



Plate, LVII/; fig. 10. 



This is the smallest species of the genus yet known. It is represented 

 by many mandibular rami, the best preserved of which supports the last 

 four molar teeth. 



In the last ta'ue molar the anterior external cusp is larger than any of 

 the others. There is a minute anterior inner. The external lateral is the 

 apex of a crescentoid crest; the corresponding inner one is smaller, and is 

 part of the raised border, which culminates in a small median tubercle pos- 

 teriorly. The first and second true molars are narrowed in front, and there 

 is no distinct anterior ledge, only a minute anterior inner tubercle. The 

 external cingulum is more distinct and the enamel is wrinkled. The fourth 

 premolar has a short base, and the inner cusp is much smaller than the prin- 

 cipal one ; it has a wide heel and an anterior basal tubercle. Length of 

 true molars, M. .018; of last true molar .006; of first true molar .006; 

 width of do. .004; depth of ramus at do. Oil. 



The anterior border of the masseteric fossa is well marked to the mid- 

 dle of the depth of the ramus. The fossa is elsewhere undefined. 



From the Puerco epoch of Northwestern New Mexico; D. Baldwin, 



