OCR Text |
Show 230 DR. J. ANDERSON ON ASIATIC SHREWS. [Mar. 4, mens of P. indica. The front incisor has no internal process; and the basal tubercle is obtuse and rather small. The dental formula is AT + ^ + lrl=30- In the tnree foregoing types, the lower incisor is either quite smooth or provided with a small eminence. I shall now point out the peculiarities in the dentition of another Shrew, the Crossopus himalaicus, Gray. That most assiduous naturalist referred this Shrew to the genus Crossopus, Wagler, in a restricted sense. The only information he gave regarding its dentition was, that the cutting-teeth were ^2, which is sufficient evidence that in its dental formula it must have been nearly allied to Sorex. He considered it, however, to be a true Crossopus. Blyth also had his doubts whether it had been correctly referred to Crossopus. There is a specimen in this museum from Darjeeling, which agrees in every particular with the external characters as given by Gray and Tomes ; and another from Ponsee, in the Kakhyen bills, to the east of Bhamo, Upper Burmah; but the dentition is not that of a Crossopus. The teeth are wholly white ; there are only three small lateral incisors ; the front incisor has a rather small, obtuse, basal process ; but the inner margin of this tooth, unlike any of the forms referable to the preceding groups, has a small process developed on it. It is rather obscure, but has all the characters of the process as it occurs in the other two brown-toothed genera of Shrews recognized by Brandt. The teeth, however, of this form, as I have already mentioned, are white ; the lower incisors are smooth ; and the teeth.in all their other characters, with the exception of this process, agree with the section to which C. aranea belongs, the dental formula being *****^ + 2 +2+6 ='*'''--'' ^ e Pr e s e n c e °f this process in this species serves to link the white- to the brown-toothed Shrews; but this character of itself, occurring in the feeble way it does, is not a sufficient reason for separating it generically from Crocidura. The genus Crocidura may therefore be defined as follows :-Teeth white ; first incisors arched, provided with a more or less obtuse moderately developed tubercle at their base posteriorly. The inner margins usually smooth, or provided with a feeble tooth-like process. Lower incisors long, curved forwards and upwards, smooth, or provided on their upper surface with one or more eminences; small lateral teeth varying from two to four. The following Table is the result of an examination of the dentition of the various white-toothed Shrews in this museum, from which it appears that three of them belong to the genus Crocidura, as above defined, and the remainder, 10 in number, to the type of dentition represented by Pachyura indica. White-toothed Shrews. A. Front incisors of upper jaw without an internal process. Crocidura kelaartii, Blyth. -~ +2 + 2+6 = 28. Lower incisors smooth. Intermaxillary suture examined. Probably young of some other species. |