THE EYE OF THE COMMON MOLE, SCALOPS 

 AQUATICUS MACHRINUS. 



By James Rollin Slonaker, Ph. D. 



{From the Neurological Laboratory of the University of Chicago.) 

 With Plates XVIII to XX. 



Introduction. 



During recent years a number of investigations have been 



made on degenerate and rudimentary eyes. Among the most 



important investigators may be mentioned : Heape (3), Kohl 



(4), RiTTER (5), Rabl (6), Hamann (7), Retzius (8), Lankes- 



TER (9), ElGENMANN (lO), FORBES (l l), PACKARD (l2), and 



Cunningham (13). 



The first four named have made important studies on the 

 eye of the European mole {Talpa eitropcBa). So far as I know 

 the eye of the common American mole {Scalops aqiiaticiis) has 

 not been studied. Four varieties of this species have been 

 described by True (i). It is the common mole, or variety 

 machtinus that I speak of in this paper. 



Though there is a great similarity existing between the eye 

 of Scalops aquaticus macJiriniis and the description of Talpa 

 europoca as given by the above mentioned authors, I find some 

 important differences. These will be mentioned later. 



General Appearance. 



The head of the mole is conical in shape, the nose or 

 snout forming the apex. The fur gives it a regular contour. 

 So dense and fine is the fur that it wholly conceals the ears and 

 eyes. These may be seen, however, if one parts the hairs at 

 the proper places. The position of the eyes may be readily 

 seen if the hair is closely shaved from the head. When this is 

 done the eyes appear as dark areas, almost one millimeter in 



