216 Description of a new species of Mole. [No. 3, 



But the characteristic distinction of T. leucura consists in having 

 only two small premolars in the upper jaw anterior to the great last 

 premolar (carnassiez, or ' scissor-tooth') ; both T. europcea and T. 

 microura having three, — these being comparatively larger and less 

 separated in the latter, and the carnassiez is also much larger in T. 

 microura than in T. europcea. The posterior spur of the canine ( ? or 

 pseudo-canine*) is remarkably developed in T. leucura, in place of 

 the absent small prsemolar. In the dentition of the lower jaw, there 

 are also characteristic differences distinguishing these three species. 

 In the Moles, as in most other Insectivora, and also in the Lemuridce 

 (the very peculiar genus Cheiromys, which has rodential tusks, except- 

 ed), the lower canine is minute and takes the form of an incisor, for 

 which it has been very commonly mistaken ;f and the first prsemolar 

 is developed to assume the form of a canine, but locks posteriorly 

 to the upper canine (or pseudo-canine, and like it has a double fang). 

 There is no instance of a genuine lower canine locking behind the 

 upper one, unless the gnawing tusks of the Rodentia and of the Lemu- 

 ridous Cheiromys be regarded as the homologues of canines, which 

 seems to be indicated more by the co-presence of undoubted upper 

 incisors in the Leporidce, than the reverse is by the difficulty of always 

 tracing the origin of upper rodential tusks through the intermaxil- 

 laries to the true maxillary bones in the rodents generally. But to 

 return to Talpa leucura : following the minute lower canine and the 

 canine-like first lower prsemolar of this species, there are two small 

 prsemolars anterior to the carnassiez or last of the series, and the first 

 of these is conspicuously much smaller than the second ; in T. microura 

 the two are of equal or nearly equal size, and occupy more space 

 longitudinally ; while in T. europcea these and the carnassiez successively 

 enlarge in a regular gradation, the latter being proportionally smaller 



* In all the Insectivora, Cuv., which apparently possess upper canines, these 

 teeth have rather the structure of modified false molars, and, I believe, have always 

 double fangs, as exemplified by Talpa, Centetes, and Gymnura. I figure the upper 

 pseudo-canine of Talpa europcea extracted from its socket, by way of illustration. 



•f- No placental mammal has more than three pairs of true incisors, or than three 

 pairs of true molars (distinguished by their not being preceded by deciduary teeth in 

 the young animal, as is the case with all other teeth) . Although certain instances 

 occur, as especially in the hoofed ruminants, where the lower canine is hardly (if 

 at all) to be distinguished from the incisors, yet this fourth supposed pair of 

 incisors never co-exists with an undoubted canine (vide the Camels, Horses, Tapirs, 

 &c), that is among the placental mammalia, inasmuch as they are the veritable 

 homologues of those teeth. 



