316 PALAEONTOLOGY 



fossils discovered there by Mr. W. E. Brodie, and transmitted 



for determination in 1854 to the writer, amongst the remains 



of fishes and small Saurians, constituting the majority of the 



specimens, were detected three unequivocal evidences of a 



mammalian species, which were described under the name of 



SpcUacotheriwn* tricusjridens. 



The specimen here selected 



(fig. 90) to exemplify the 



above extinct insectivorous 

 Fig. 90. 



Spalacotherium trkuspidens (twice nat. Mammal, is a right ramus of 



size), Purbeck beds. fl ie l ower j aw . The posterior 



half contains four teeth, and extends backward beyond the 

 dental series ; but instead of showing the compound structure 

 which that part of the jaw exhibits in the Lizard tribe, it con- 

 tinues undivided ; the convex surface showing a smooth 

 depression for the insertion of the temporal muscle ; the lower 

 boundary answering to that going to the condyle and angle of 

 the jaw, and the upper one to that going to the coronoid process 

 in the ramus of the jaw of the mole and shrew. The crowns 

 of the teeth are long, narrow, and tricuspid, the inner part of 

 the crown being produced into a point both before and behind 

 the longer cusp winch forms the chief outer division of the 

 crown. Each of these teeth is implanted by a fang divided 

 externally into two roots, in a distinct socket in the substance 

 of the jaw. The multicuspid crown, the divided root of the 

 tooth, its complex implantation, and the undivided or simple 

 structure of the ramus of the jaw, all concurred, therefore, to 

 prove the mammalian nature of this fossil. 



The other specimens showed that the 8pcUacotheriwm had 

 ten molar teeth in each ramus of the lower jaw, preceded by a 

 small canine and incisors. The anterior molars are compressed, 

 increase in height and thickness to the sixth, and from the 

 seventh decrease in size to the hindmost, which seems to 1"' 



* From mra\a{, a mole ; Prjpior, a hcast. 



