48 University of Michigan 



be seen from the scale (50 microns), some of the cusps ap- 

 proach the Hmits of microscopic visibihty. This radula ap- 

 pears to Ije similar to that of Adclopoma iucuia Doehring 

 (1884); it certainly does not resemble those of the Apero- 

 stomatinae. 



Description of Plates 



All drawings are made with the aid of the camera lucida. 

 Under the number of each figure, is a hair line, which repre- 

 sents an actual length of one millimeter in plate II, and 50 

 microns (.05 mm.) in plates III and IV, and in the text-fig- 

 ures. 



