1854.] OWEN PURBECK FOSSILS. 429 



cingulumor ridge; beneath which the two fangs, or the two external 

 fangs, descend into the substance of tiie jaw. 



In the state in which this most instructive portion of the Spalaco- 

 there was presented to rne, the matrix concealed all save the large 

 middle cusp of the molar teeth, which teeth then seemed to be wider 

 apart, and presented a more lacertine aspect. By the careful appli- 

 cation of a fine needle and graving tool, I succeeded in displaying the 

 lateral cusps and grinding surface of the crown, and the other teeth, 

 as shown in the enlarged view given in fig. 10. 



Fig. 10 a gives a magnified view of the antepenultimate molar, 8, 

 viewed obliquely from behind ; and fig. 10 5 is an outline of the crown 

 of the same tooth, viewed vertically : these figures accurately repre- 

 sent the mammalian and insectivorous characters of the teeth. 



So much of the jaw-bone as is preserved in this specimen, fig. 10, 

 corresponds in size and shape with the portion and impression of the 

 opposite (left) ramus, fig. 9 ; and shows the same vertical contrac- 

 tion or decrease of diameter behind the molar series, prior to the ex- 

 pansion of the jaw into the ascending ramus. The horizontal ramus 

 has suffered an oblique fracture since its fossilization across the 

 alveolar series, with a very slight depression of the fore part contain- 

 ing the four anterior teeth : a second fracture crosses the contracted 

 part of the jaw behind the last molar in place. There is not any 

 clear evidence of a smaller molar tooth behind the last in place, 

 marked 10. Between the large laniariform tooth, c, and the fore end 

 of the ramus of the jaw, there is space for three incisors like the small 

 one preserved, i, and also for a small canine, which tooth is demon- 

 strated in one of the specimens (« 7) in Mr. Brodie's collection. 



The specimen marked e 7 in this series is the anterior half and an 

 impression of most of the remaining part of the left ramus of the 

 lower jaw, with its inner surface exposed, showing the large canine 



Fig, 11. — Inner aspect of a left ramus of the lower jaw, with teeth, 

 of the Spalacotherium tricuspidens, Owen. (Nat. size, and 

 magnified.) 



10 9^8 7 e .^ /, 3 



r "^ 



a. Two molars, numbered 4 & 5. c. Premolar or canine ? tooth. 



or canine-shaped premolar, c, and five following teeth in place, a frag- 

 ment of a sixth molar, and impressions of four succeeding molars. 

 The crown of the canine-shaped tooth is long, subcompressed, slightly 

 recurved, pointed, with a posterior basal tubercle. The adjoining 



