536 



C. H. EDMONDSON AND R. H. KINGMAN. 



the shell has the appearance of being distinctly punctate. In some 

 individuals the punctae are arranged in a regular diagonal manner, 

 in others there is no regularity about the arrangement. In no 

 specimens examined can outlines of plates be detected even with 

 the oil immersion lens. 



The neck is short and sharply bent, nearly at right angles to the 

 long axis of the shell. The circular aperture is bordered by a thin 

 delicate membrane of approximately 4/i in breadth. 



A number of short, blunt, tooth-like prolongations are present on 

 the posterior border of the fundus. From three to seven of these 

 processes are usually present. They vary in size and when numerous 

 give an irregular, crenulated appearance to the posterior edge of the 

 fundus, when the broad side of the shell is viewed. 



In Leidy's species the two horns are directed laterally and pos- 

 teriorly, their tips not projecting beyond the posterior border, giving 

 the fundus a rounded outline when the narrow side of the shell îs 

 observed. In this species the teeth-like points are directed backward 

 and project beyond the border, giving the fundus the appearance of 

 terminating in a spine when the narrow side of the shell is seen. 



Leidy records the size of Campascus cornutus as ranging from 

 0.112 mm. to 0.14 mm. long by 0.18 mm. broad. 



This species of Japan is much smaller. The length of the shell, 

 including the spines and the collar about the aperture, ranges from 

 60 to 80/t. Breadth of fundus from 50 to 66p.. 



Greatest thickness, narrow view, 28^. Aperture 12/i in diameter. 

 The living organism was not observed. 

 P animella Lauterborn. P. chroviatophora Lauterborn (fig. 19). 



Empty shells of this very minute form were found in material 

 from the bottom of Lake Hakone and also from shallow lakes on 

 Mt. Rokkozan. The shell is composed of five longitudinal rows of 

 plates and possesses a short neck. The Japan form is very 

 typical. 



