25 



Of the incisor teeth, the supposed lower third, figs. 6 and 7, is very similar in shape to the 

 canine, but is smaller, less pointed above (worn), and the breadth of the crown below is greater 

 than the height. The crown is set obliquely to the root. The left lower incisor, figs. 8 and 

 9, probably the first, is considerably worn above where the greatest breadth occurs. Its 

 cutting edge forms an almost straight line across, and the later margins slope gently inward 

 to the root, without the abrupt basal constriction observed in the third incisor. Internally 

 the crown is concave, with a median longitudinal rib. 



ANTHRACOTHERIUM? PYGMiEUM, sp. UOV. 



Plate VI, fig. 6. 



A right upper molar of very small stee indicates an artiodactyl with dental characters 

 suggestive of an Anthracothere. As the tooth is imperfect, lacking some of the parts most 

 essential for its exact determination, a description of it is given, in the hope that at some 

 future date, better material may be forthcoming. For the present it is referred to Anthraco- 

 therium, but it is probable that an undescribed genus is represented. For the species the name 

 pygmceum is proposed. 



In crown view the outline of the tooth is quadrangular, with the antero-posterior diam- 

 eter internally greater than the anterior transverse diameter, so that the tooth is longer than 

 broad. In Anthracotherium and Ancodus these proportions are reversed. The margin of the 

 tooth is perfect anteriorly and internally, but externally and posteriorly it is damaged. The 

 specimen lacks the mesostyle and the posterior slopes of the metacone and hypocone. The 

 four main cusps are crescent ahaped and there is a distinct but small protoconule. 



A deep transverse valley separates the anterior from the posterior cusps, a comparatively 

 shallow longitudinal valley occurs between the protocone and the paracone, but a correspond- 

 ing valley does not exist between the hypocone and metacone. The protocone is larger and 

 more elevated than the hypocone, but both are prominent with steep inner slopes. A broad, 

 median rib occupies the outer, otherwise slightly concave slope of the former. The paracone 

 is low (in the specimen much worn), but the metacone rises nearly to the height of the 

 hypocone, whose outer slope is short, and descends but little to meet it. The outer slope 

 of the paracone (judging from the small portion of it preserved) resembled that of the proto- 

 cone. The anterior spur of the protocone reaches to the protoconule, which is close to a well- 

 defined anterior cingulum. The posterior spur of the protocone is long, crosses the median 

 transverse valley, and rises on the anterior slope of the hypocone nearly to the apex of the 

 metacone. The basal cingulum occurs on the anterior face of the crown, and in the inner end 

 of the transverse valley The anterior spur of the hypocone connects with the posterior spur 

 of the protocone almost at the apex of the metacone. The specimen shows the junction 

 of the anterior spur of the metacone with the posterior one of the paracone, but the mesostyle 

 is missing. The parastyle is very feebly developed. 



The approximation of the posterior cusps in this tooth is a character probabby sufficient 

 to distinguish the species generically from any of the known genera of Anthracotheriidce. 

 The selenodont form of the main cusps, and the presence of a protoconule, makes it most 

 probable that this species is properly assignable to the Anthracotheriidce. The tooth pattern 

 indicates a closer relationship to Anthracotherium than to Ancodus. 



12529—4 



