MAMMALS TALPIDAE SCALOPS ARGENTATtfS. 63 



SCALOPS ARGENTATUS. 



Silver or Prairie Mole. 



Scalops argentatus, AUD. & BACH. Jour. Acad. Nat. Sc. Phila. VIII, 11, 1842, 292. IB. N. A. duad. HI, 1853, 252 ; 



pi. cl, f. 4. 

 WAGNER, in Wiegm. Archiv, 1843, 11, 31. IB. Suppl. Schreb. V, 1855, 573. 



Sp. CH. Larger than S. aquaficus. Teeth 36. Eyes and ears very minute, the former covered by the integument. Nostrils 

 antero-superior. Palms scarcely broader than long; tail nearly naked. Color silvery plumbeous. 



This species is very similar to the S. aquaticus, and smaller specimens are with difficulty 

 distinguishable from the latter ; indeed, it may be a question whether the two can with entire 

 propriety be separated. The combination of the larger size, more silvery color, and more 

 western locality, may, however, substantiate the claim of S. argentatus to a separate place. 



The muzzle is elongated and depressed, the nostrils opening on its antero-superior truncation, 

 much as in S. aquations, but rather more superior. The anterior face of the upper incisor is a 

 little anterior to a point midway between the eye and the tip of the nose. The eye is visible 

 as a small bluish speck through the integument, which is not pierced even by a pin-hole aper 

 ture, as in S. aquaticus. It is placed a little behind the posterior angle of the jaws. The ear 

 is represented only by a circular meatus, about the twenty-fifth of an inch in diameter. 



The palms are very large, with the claws but little longer than broad. The hind feet are 

 about as long as the anterior ones, but much narrower. The amount of webbing to the feet is 

 much as in S. aquaticus. 



The general color of this species is a light silvery plumbeous brown, not very dissimilar to 

 that of freshly cut lead. The under parts are a little lighter, especially just back of the arms ; 

 a more brownish tint is usually imparted by immersion in alcohol. The prevailing color of the 

 feet and tail is white, the latter rather more densely hairy than in the aquaticus, as well as 

 longer. 



The Scalops argentatus is sufficiently distinct in its characters to require comparisons only 

 with S. aquaticus. The size is much larger, the general proportions similar. The nostrils are 

 more superior ; the head more slender ; the eye is entirely covered by the integument, which 

 extends over the ball, instead of being pierced by an orbital opening. The ear is a little larger. 

 The color is much more silvery in its lustre, without any brown. 



The difference in the size of those species is very appreciable in the skulls, of which I subjoin 

 the comparative dimensions of the largest specimens in the collection of each. 



The skull exhibits the dentition of S. aquaticus in having 36 teeth ; or, according to the 

 determination of Owen, incisors^, canines ^,premolars 3^3, molars jj^. In the upper jaw 

 the anterior incisor is very large and rodent-like ; the two lateral on either side are very small 

 and thread-like, and quite deciduous. The canine is moderately thick and prismatic ; the three 

 premolars are similarly shaped, and increase successively from first to third ; the anterior 

 smaller, the middle larger than the canine. All the teeth in the jaws are separated by 

 diastemata. 



By the decadence of the small lateral incisors, the number of teeth may be reduced to 34 or 

 32. The anterior lower incisor is also very small, and sometimes wanting, making the teeth 

 30 in number. 



