1886.] NATURAL SCIENCES OF PHILADELPHIA. 361 



ently supported on single fangs. The crowns are subcylindrical, 

 with obtuse tips. The third premolar is larger, more tapering 

 from base to summit, and has an indication of a double fang. 

 The first molar in general outline is transitional between the 

 molars and premolars. On the anterior slope of the main cone, 

 near the summit, is a fine accessory cusp ; while near the base of 

 the posterior slope is a more distinct cusp. The second molar 

 has two accessory cusps on the anterior slope of the main cone, 

 and one on the posterior slope placed half way down. The 

 third molar differs from the others in the large size of the poste- 

 rior cusp. On the anterior slope there is an indication of a 

 small accessory cusp. In the fourth molar the crown tip is de- 

 tached, but there is an indication of the usual anterior and posterior 

 accessor}^ cusps. The fifth molar, besides the anterior and poste- 

 rior cusps, has the trace of a posterior cingulum and possibly of a 

 postero-external cusp. The sixth molar is like the fourth. The 

 seventh molar is the most complex tooth in the series ; like the 

 second, it has two accessory cusps on the anterior slope of the 

 main cone, the uppermost of which is distinctly bifid. The 

 posterior slope also has a bifid accessory cusp, and a faint basal 

 cingulum. The anterior cusps throughout rise like needle-points 

 on the sides of the teeth ; the posterior cusps are more distinct. 

 All the molars are compactly placed with high, rather narrow 

 crowns, and deep depressions above the double fangs. The char- 

 acters of these crowns were made out with the greatest diflSculty, 

 and a more perfect specimen may show slight difference of 

 detail. 



The mandible of Dromatherium is heavy and well-rounded in 

 section. It is marked on its inner face by a deep mylohj'oid 

 groove, widening posteriorly into a broad pterygoid fossa. 

 The upper border rises behind the molars into the coronoid pro- 

 cess, cr. The summit of this process is broken, but a faint impres- 

 sion on the matrix shows that it had a high, slightly recurved 

 outline. A small portion of the hind border seems to be pre- 

 served just above the angle which would indicate that the condyle, 

 cr?, was placed midway between the coronoid and angle, somewhat 

 as in Amblotherium. The thick lower border has a gentle double 

 curvature. There is no trace of the symphysial surface. 



The unique character of the dentition separates Dromatherium 

 widely from any known fossil or recent genus. 



