Il6 EDWIN LINTON. 



ends. In this condition they were sometimes straight and some- 

 times arcuate (Fig. i). In each sporocyst there were tailed cer- 



FiG. I. Contraction shapes of sporocysts, life. 



cariae along with various stages of developing cercarise, from 

 globular balls of cells, 0.04 millimeter in diameter, to cercariae, 

 0.5 millimeter or more in length (Fig. 2). The anterior portion 



Fig. 2. Sporocyst showing cercarise in different stages of development. Cam- 

 era lucida sketch of stained and mounted specimen. Actual length 1.04 millimeter. 



of these cercarise is sub-cylindrical and slightly tapering at the 

 anterior end. It is marked off from the elongated tail portion 

 by a constriction, which, in the mature cercarise, is at about the 

 anterior fourth of the entire length. In other words, the tail, 

 which is forked at the end, is about three times the length of the 

 body. Along the dorsal aspect of the body in a few instances a 

 longitudinal row of exceedingly slender spines was noted. As 

 this cercaria resembled very closely a cercaria which I have 

 found in the scallop {Pecten irradians), I recorded in my notes 

 that it was likely that these spines, as in the cercaria from the 

 scallop, are remnants of a fin-like membrane, and that the type 

 represented by this cercaria is evidently near that of Cercaria 

 cri lata h^ Val. 



