.,20 ON THK structure AND CLASSIFICATION 
,he ox, q, lion Of the additional tubercle upon the two posterior. In both genera 
the pron'okrs decrease in size nntero-posteriorly. The first molar o CAnm has un- 
won' valleys between the tubercles and a smooth inner face as in m and m of liolodon-, 
while the .second molar resembles and m' of BoMou in the signs of antero-posterior 
wear between the tutarclcs. For these reasons I am inclined to regard C7, urn as a 
successor of liolodon, or as having a relation somewhat similar to that which may have 
obtained between Polymadodon and Tritylodon. 
3. TRITYLODONTIILF, Cope >, 1884. 
TRITYLODON, Oweu*,1884. 
Dentition, i ? c ° pm and m !!. One large median vertical incisor is followed 
by a small incisor and this by a wide diastema. Behind this are two teeth with 
broken crowns, the foremost or both of which may represent premolars. Behind these 
are four quadrate molars with three parallel rows of conical tubercles, separated by 
well worn grooves. In m'’ to m'^ 
inclusive there are three tubercles in 
the inner row, four in the middle 
row and two in the outer row. In 
the sixth molar the tubercles are 
less numerous. The face is elongate. 
The frontals do not join the pre- 
maxillaries. The parietals diverge 
anteriorly into a wide depresson.^ 
Fiai’KK 13. Tritylodon lonaaviis, anterior portion of the rni in i ii i i j 
-knli viewed u,»on the left face, two thirds natural size, ^he lachrymals are well developed 
.\nert)wen. upon the face, and the foramen is 
intra-orbital. The anterior nares are terminal. The posterior nares are between the 
fifih and sixth molars. 
TRIGLYPHUS. Fraas 1868. 
1 his genus is represented by a single molar which closely resembles in the num- 
l)er and disjiosition of its tubercles the molars 3 — 5 of Tritylodon, as pointed out by 
NeumayrV AVhen these teeth are closely compared (fig. 6, i and 2 ), they will 
jirobably prove to belong to the same genus, in which case Prof. Fraas’ genus has the 
l)riority. 
' .American Naturalist, loc., cit. 
• Quart. Joiirn. of the Geological Society. Dr. George Baur kindly investigated this skull at my request 
and reports that there is no trace of a foramen here. 
• Discovereti in the Rha-tic Beds near Stuttgart and described by Prof. Fraas in his work, “ Vor der Sund- 
fluth/* page 215. 
‘NeuesJahrbuch.f. Min., Geol., und Pal.. 1884 ., p. 279 . 
