NO. 1101. PROCEEDINGS OF THE NATIONAL MUSEUM. 15 



may be remarked tliat tlie minute teeth of the upper jaw have milk 

 l^redecessors. 



In view of what has just been stated, the formula, i, f ; c, |, ought to 

 be used in comparative tables for the permanent dentition, but, of 

 course, with the explanation that the formula i, |, c, ^ represents the 

 functional dentition, so far as incisors and canines are concerned. 



In the case of the genus Condylura the material at command is insuf- 

 ficient. None of the young skulls have more than a small part of the 

 milk dentition, and they are also broken in such a manner as to defeat 

 critical examination. In skull No. 2094, Bangs' collection, the fourth 

 upper tooth stands in the suture and may be recorded as a canine. 

 The formula, according to the suture, therefore, would be i, |; c, |; 

 pm, I; m, §, which must be accepted at least until the full milk denti- 

 tion can be examined. 



In the genus Netlrotriclius there is no tooth in the series anterior to 

 the molars Avhich has not a milk predecessor. There are three teeth in 

 each side of the premaxillary bone, and in the suture api)ears a large 

 fourth tooth, which must be reckoned as a canine. The milk prede- 

 cessor of this tooth stands behind it quite independently, the large 

 tooth pointing backward and the small one forward. The two teeth 

 which come next have milk predecessors implanted over them. Thus 

 it appears that there is no premolar without a predecessor. It is only 

 natural to suppose that the first premolar is absent and that those 

 which are i^resent are the second and third. Allowing this to be the 

 case, we have, deciding by the suture, the following formula: i, |; c, -f ; 

 pm, f; m, f . 



This is the same as the formula adoi)ted by Dob.son. 



To summarize, the formuhe of the different genera are as follows: 



Scalops, i, il 1 ; c, j ' ; pm, § ; m, f . 

 Scapaniis, i, |; c. j; pm, |; m, |. 

 Parascalops, i, § ; c, | ; pm, | ; m, f . 

 Condylura, i, § ; c, i ; pm, i; m, f . 

 Xeurotrichus, i,^; c,\; pm, |; m, f . 



COLOR OF MOLES. 



The color variations of moles are of much interest, as the style of 

 coloration is of the simplest character, and the complexity caused by 

 the appearance or disapi»earance of spots, lines, etc., is absent. The 

 various species belonging to the several genera do not exhibit the same 

 degree of variation, Parascalops, Condylura, and Neiirotrichus exhibit- 

 ing but little, Scapanus a moderate amount, and Scalops more. 



The variations of Scalops are geographical, the main departure from 

 the mean of coloration being in the Northwest and Southwest. In the 

 Mississippi Valley generally, but particularly in southern Minnesota 

 and Wisconsin, there is a tendency to increase in pallor, producing a 



^ Persistent canines and incisors =i, f ; c, ^. 



