1904.] 



PECULIARITIES IN CERTAUsT MAMMALS. 



423 



from the Oligoeene White River Beds of North America *, in 

 which there are four minute teeth between the molars and the 

 large incisor, making eight mandibular teeth. It was therefore to 

 be foreseen that in later Tertiary deposits would be found Soricidfe 

 with the number of lower teeth intermediate between the number 

 occurring in the Oligoeene and that in the recent Shrews, viz. 

 seven. In fact, I find that in the " Sorex -pusillus H. v. Mey., 



■ Soi'e.v pusillus, var. grivensis" aiitevioi' portion of left mandibular ramus : 

 A, outer ; B, inner aspect. 



var. grivensis Dep.," which is not unfrequent in the Middle Miocene 

 of La Grive- Saint- Alban (Isere), a diminutive tooth was pi*esent 

 between the two minute intermediate teeth ; it has in most' 

 specimens dropped out, but its alveolus is invariably present. The 

 specimen figured is a fragment of the left mandible containing 

 five teeth, viz., from fore to back, the procumbent incisor (the 



* Proc. Ac. Nat. Sci. Pliilad. 1894-, pp. 446-448 (1895). 



