188 



BULLETII^ 16 9, UNITED STATES NATIONAL MUSEUM 



"Measurements 



Length of ma 9.7 mm. 



Width of ma 8.4 mm. 



Length ma 9.6 mm. 



Width of ms 7.6 mm. 



Depth of jaw atm2 -- 16.0 mm. 



"Unfortunately, as in the type of A^. silberlingi, the enamel of the 

 molars has been considerably damaged through weathering or leach- 

 ing by surface water, which somewhat obscures the detailed structure. 



''The generic reference is provisional, since certain features, as the 

 straight and more slender proportions of the jaw and relatively greater 

 width of the lower molars, so sharply distinguish A^. latidens from all 

 other species of this genus or of Claenodon. They suggest that its 

 afl&nity to the group to wiiich I here assign it may be, after all, not very 

 close. More complete and better preserved material may, therefore, 

 necessitate placing it in a distinct genus." 



a 



FiGURK a.— Claenodon latidens (Gidley), U.S.N.M. no. 8388, with parts in outline probably adapted from 

 other species nf Claenodon, risht lower jaw: a, Crown view; 6, external view. Natural size. (After Gidley, 

 1919, fig. 10.) 



Discussion. — The apparent differences from C. montanensis in the 

 shape of the mandibular ramus are, in my opinion, illusory and due to 

 the different preservation of the two specimens. The jaws appear to 

 have been almost identical or at least well witliin the possible range for 

 a single species. So far as available material goes, the species depends 

 wholly on the notably wider M2_3. That this is of specific value is not 

 certain, especially as the size is otherwise that of C. montanensis and 

 both are from the same quarry, but the species may be tentatively 

 retained. I see no reason to suspect that a new genus is represented. 



