PALEOCENE MAISIMALS OF CENTRAL UTAH GAZIN 



51 



some lower jaw fragments with incomplete teeth and found associ- 

 ated, is made the type (fig. 29). The teeth are close in size to those 

 of the nearly contemporaneous Conacodon cophater but more closely 

 resemble those of species of Haploconus. The form is distinctly 

 smaller than either Haploconus angustvs from the Torrejon or Hap- 

 locojiKS inophuitus from the Dragon horizon. 



M^ and M^ resemble these teeth in E. inopinatm, but in addition 

 to their smaller size do not show so marked a difference between 

 their transverse diameters as in H. inopinatus; moreover, the upper 

 molars are relatively a little shorter antero- 

 posteriorly. The protocone is distinctly 

 lingual in position, approaching, but not 

 reaching, the condition seen in Conacodon 

 cophater. There is a slight protostyle at the 

 lingual termination of the anterior cingulum, 

 not so well developed as in H. inopinatus, nor 

 does the anterior cingulum extend so far 

 lingually as in C. cophater. In the latter 

 form the anterior cingulum quite joins the 

 protocone lingually in M^ and M\ H.f 

 elachlstus also differs noticeably from C. 

 cophater in the weakness of the external 

 cingulum. As in later forms of Haploconus, 

 the external cingulum in H.f elachistus does 

 not extend across the paracone. 



The anteroposterior diameter of M' in the 

 type is 3.6 mm. The transverse diameter 

 from the external cingulum to the base of 

 the enamel lingually and at right angles to 

 the direction of the tooth row is about 6.1 



Figure 29. — // aplocov us? 

 elachistus, new species: Por- 

 tion of left maxilla with M* 

 and part of Ml (U.S.N.M. 

 No. 16191), type specimen, 

 lateral and occlusal views, 

 X 3, Wagonroad Paleo- 

 cene, Utah. 



mm. 



The lower teeth are much like those in 

 Haploconus angustus, except for their 

 smaller proportions. However, the various lower molars referred 

 to H.f elachistus exhibit a slight, medianly placed paraconid. This is 

 also true of P4 in No. 16548, although P3 in the same specimen, 

 though not entire, shows no evidence of a paraconid. It is interesting 

 to note that slight paraconids were observed on the lower molars of 

 a Torrejon specimen, U.S.N.M. No. 5886, referred to Haploconus cor- 

 niculatus, as well as on one of the Dragon specimens. The paraconids 

 of the lower molars of H.f elachistus, however, are not developed as 

 seen in M^ of Conacodon cophater, nor is the talonid portion so com- 

 pressed anteroposteriorly, and the entoconid, though very well defined, 

 is not placed so far lingually. 



