| OCR Text |
Show 1904.] PECULIARITIES IN CERTAIN MAMMALS. 423 from the Oligocene 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 Soricidae with the number of lower teeth intermediate between the number occurring in the Oligocene and that in the recent Shrews, viz. seven. In fact, I find that in the " Sorex pusillus H. v. Mey., Text-fig. 82. " Sorex pusillus, var. grivensis," anterior 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 present 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. Philad. 1894, pp. 446-448 (1895). |
