MAMMALS TALPIDAE SCALOPS AQUATICUS. 59 



penultimate upper molar is trapezoidal, nearly triangular in cross section, instead of subquad- 

 rate ; the one anterior to it is also trapezoidal, instead of lozenge shaped. Viewed externally, 

 there is a small acute lobe on the anterior edge of the last premolar, and all the molars, close 

 to the base of the crown ; and there is a similar lobe on the inner edge of the corresponding teeth 

 of the lower jaw. The molars are in close contact ; the teeth anterior to these, in the upper jaw, 

 are separated by diastemata. The lower incisors are of nearly equal size, the second not larger 

 than the first. The nostrils are near the end of the muzzle, either lateral or superior. The 

 tail is more or less hairy. 



The chief differences in dentition between Scalops and Scapanus, then, are in the greater num 

 ber nf teeth in the latter ; the greater permanence and more uniform size of the incisors and 

 premolars ; the anterior basal fang to the last premolar and the molars, and the different shape 

 of the molars. Other distinctions might be enumerated, but at the risk of pursuing the subject 

 into too great detail for my present purpose. 



To the restricted genus Scalops belong at present three species : S. aquaticus, inhabiting the 

 whole eastern portion of the United States, from Massachusetts to Florida, and west to Missis 

 sippi and Alabama ; S. argentatus, a prairie species, ranging from Michigan, through northern 

 Ohio, Illinois, Missouri, northern Louisiana, Arkansas, Kansas, and Nebraska, as far at least 

 as the Upper Missouri ; and S. latimanus, found in Mexico, and stated also to occur in Texas. 

 No specimens of the latter have come under my notice. 



Of Scapanus there are two very distinct species, one found in Massachusetts, New York, and 

 northern Ohio, (S. breweri,) the other, (S. townsendn,) in Washington and Oregon Territories, 

 Whether the California mole, called Scalops californicus by Ayres, be really distinct from S. 

 townsendii can only be shown by additional specimens ; if the same, the range of S. townscndii, 

 will extend from Puget Sound to San Francisco. 



The European analogue to the American mole, though so similar in mere external form, yet 

 differs by so many striking peculiarities of dentition as to render it a matter of very great sur 

 prise that authors at this late day should have thrown both into the same genus. To illustrate 

 the differences, I subjoin the chief characters of Talpa, 



Talpa. Teeth 44 in number. Formula : incisors |^> canines l ~, premolars ^ molars ^ 

 = j| = 44. The three incisors on each side of the upper jaw are very small and uniform in 

 size, (except in T. coeca, where the middle ones are rather largest,) then succeeds a well devel 

 oped canine, curved, compressed, and trenchant, implanted by two roots, followed by three 

 compressed premolars of similar size and shape, with two fangs each ; then a fourth premolar, 

 trihedral with three (?) roots. All the premolars of the lower jaw have double roots, the 

 anterior largest, simulating a canine ; the canine itself separated from the premolar by a dias- 

 tema, and not distinguishable from the incisors in shape. 



The nostrils are strictly terminal, and open antero-inferiorly, so as to be visible from below 

 and not from above, the reverse of what is the case in the American moles. 



It will thus be seen that Talpa differs from Scalops in the small size of the anterior upper 

 incisors, the large upper canine, and the double roots to all the premolars, except the last, which 

 has three. In Scalops the premolars, except perhaps the last, have simple roots 'only. In 

 Talpa the nostrils are terminal, and antero-inferior. Condylura agrees with Talpa in the double 

 rqpts to the premolars. 



