THE MAJIMAIJA OF THE UINTA FORMATIOX. .')2'{ 



Other measuremenls may be obtained from tlic plates, which aiv caivfiilly ihMwii 

 to scale. 



Dentition, Comparatice i/easurement». 



Upper Upper m' m' Lower Lower m^ tn, 



series, mohirs niitpos- trans- series, molars, antpos- antpos- 

 pm'-ni'. m'-m*. ttrior. verse. pm^-m, Wi-Wj. tcrior. terior 



hectolophus .047* .016 .018 .088* .05» .014* .023 



annectens. 

 Isectolophus .036 .012 .013 .081 .042 .012 .018 



latidens. 

 Systemodon 063 .032 .OlO.i .012 .073 .035 .010 .016 



tapirinum. 



Tlie Systematic Position of Isectolophus. 



Before discussing the relation.s of Isectolophus., we may review the grounds for 

 referring this genus to a position in or near the direct tapir line : (1) As far back 

 as the Wasatch and the overlying Wind Kiver periods, we observe, as recently staled 

 in full by Copcf that a division in the lophiodont forms is indicated by the shape of 

 the postero-e.Mternal lobes of the superior molars ; in one line they are conic, in the 

 second or side line they are flattened. The former leads to the true type of tapir 

 molar ; the latter extends into another line of genera such as II>/rachyus, in which 

 tapir characters were partly retained in the feet, but in which the teeth were i-apidly 

 departing from the tapir pattern ; (2) another feature, to which Marsh first called atten- 

 tion as characteristic of this line, is the presence of a third lobe upon the lower molars ; 

 Qi) a third feature is the absence of any considerable diastema behind the canine. 

 So much for the dentition ; the distinctive foot characters are more fully discussed 

 later, they are : (4) In the carpus, the retention of subequal maguuin and unciform 

 facets upon the lunar, and the large mc. v facet upon the unciform ; (5) the exten- 

 sion of the cuboid upon the astragalus, anteriorly and posteriorly. 



The single tapiroid mark in Ilelaletrs is the small third lobe of the last lower 

 molar ; in the llattened postero-external cusjis, as in J/yraclii/us, and in the high com- 

 pressed tarsus resembling that of Tiiplopu.% with its narrow astragalo-cuboidal con- 

 tact, this genus widely departs from the tapir line. Isectolophus, on the other hand, 

 has all these marks, and the points in which /. annectens varies from T. latiden^s are 

 all ill the direction of closer approximation to the recent tapir. 



In Systemodon of the Wasatch (Cope Collection, see Tert. \'ertebrata. I'l. J^\ I. 

 Fig. 1-2), the third and fourth upper premolars have two external lobes and a 



* Approximate r.-limiitr. 



fThc I'irimodac'tyla. Am. N'ol., 18S", p. MK). 



