﻿BOYSEN RESERVOIR VERTEBRATE FOSSILS — ^WHITE 



189 



III. Interorbital region with six irregular rows of scutes; odd scutes may or 

 may not be present between the median rows G. giganteus group 



IV. Frontal region unknown G. splienodon 



Table 1. — Stratigraphical distribution of the Glyptosaurus montanus, G. hillsi, 



and G. giganteus groups 



Class MAMMALIA 

 Order INSECTIVORA 



Family DELTATHERIDIIDAE 

 Genus DIDELPHODUS Cope 



DIDELPHODUS VENTANUS Matthew 



Figure 76 



U.S.N.M. No. 18369 (fig. 76), a badly crushed skull with left P^ 

 to IVP and both lower jaws from which all the teeth have been broken 

 (loc. No. 48FR65) ; U.S.N.M. No. 18433, fragment of left mandible 

 with M2 (loc. No. 48FR80). 



If the skull is correctly referred to this form its characters are 

 sufficiently distinctive to warrant designation as a separate species, 

 rather than citation as a mutation of D. ahsarokae. The distinctive 

 characters presented by the teeth of this specimen are : P^ two-rooted, 

 anterior and posterior cingula well developed and with minute 

 crenulations ; P^ submolariform and differs from P* only in being 

 slightly smaller; M^ exhibits several minute tubercles on the external 

 cingulum between the parastyles and metastyles. Other characters 



