28 



along the inner side of the base of the crown expanding into an anterior and a posterior 

 basal cuspj between which the crown rises in two inner and lower cones, and one outer 

 and higher cone. 



Indications of the same structure are more or less clear in the four succeeding molars, 

 which retain nearly the same fore-and-aft basal breadth. There is an empty socket of a 

 smaller molar between the last in place and the base of the coronoid, and the empty two- 

 chambered socket in front of the first molar in place may have held an anterior one of the 

 same complexity, making seven molars. There is sufficient demonstration of the multi- 

 dentate character to warrant the reference, suggested by the type of molar teeth, to the 

 genus Spalacofhcrium. 



The contour of the lower border of the ramus is not an even curve, but is slightly 

 wavy, the convexity changing to a slight concavity beneath the entry of the dental canal. 

 There is an indication of a slight vertical constriction behind the molar series, as in the 

 previously described specimens of the present genus. 



Species 2. — Spalacotherium minus, Owen. Plate I, figs. 39, 39a. 



The best preserved molar tooth in the specimen (PI. I, fig. 39, nat. size, and 39 a 

 magnified three times, in tint) shows the generic type of Spalacotherium, the ant-internal 

 and post-internal cusps meeting at the inner side of the base of the main cone. But the 

 specimen is not only inferior in size to the type species, but differs in the absence of the 

 constriction of the horizontal ramus anterior to the expansion into the ascending branch. 

 The horizontal ramus preserves, however, the degree of vertical extent forward as far as the 

 socket of the canine, which tooth is shown in fig. 34. The base of the ascending ramus 

 indicates a curve upward toward the condyle, as in fig. 38. The dentition is not suffi- 

 ciently preserved to afford any ground for generic separation ; and I therefore retain it as 

 a smaller species of Spalacotherium. 



This species is represented by a left mandibular ramus with the inner surface exposed, 

 retaining four juxtaposed teeth belonging to the middle of the dental series with indications 

 of sockets before and behind them. Two of the retained teeth are molars, the hindmost 

 yielding the Spalacothcrian type of crown as above described. The next in advance gives 

 a main cusp and indications of an accessory one in front, and a lower and more remote one 

 behind ; but the crown of this tooth is too much mutilated for precise definition. The teeth 

 are compressed. There are indications of sockets of two molars between the last in situ 

 and the ascending ramus. The premolars show a reduction of fore-and-aft breadth more 

 immediately than in Spalacotherium tricuxpidens : their crown consists chiefly of a sub- 

 compressed sharp-pointed cone. In advance of the two hinder mutilated teeth in place are 

 sockets of four others, decreasing in size, and then a large and more outwardly projecting 

 alveolus of a canine, the crown of which has left its impression. In advance of this, the 

 symphysis with the incisive alveoli has been broken off. 



