NOTE ON TREMATODE SPOROCYSTS AND CERCARI^E 



IN MARINE MOLLUSKS OF THE WOODS HOLE 



REGION.i 



EDWIN LINTON. 



In the summers of 1909 and 1910, while engaged in the study 

 of the parasites of fishes at the laboratory of the Bureau of 

 Fisheries, Woods Hole, Mass., I examined a number of inverte- 

 brates for larval stages of trematodes. The results of these 

 examinations, although rather meagre with respect to the 

 number of species found, are not without interest. 



The following species of mollusks were examined: Crepidula 

 fornicata, C. plana, Ilyanassa ohsoleta, Littorina littoria, L. rudis, 

 Modiolus plicatulus, My a arenaria, Mytilus edulis, Neverita 

 duplicata, Pecten ir radians, Purpura lapillus, Uro salpinx cineria, 

 Venus mercenaria. Besides these several species of crustaceans 

 were examined, also one annelid, Hydroides dianihus. 



Larval trematodes were found in only two species of mollusks, 

 viz. Ilyanassa ohsoleta and Pecten ir radians. No trematode 

 parasites were found in any of the crustaceans. A sporocyst 

 found in the annelid, Hydroides dianthus, has already been 

 reported.^ 



I. Sporocysts and Cercari^ from Ilyanassa obsoleta. 



Figures 1-6. 



Snails of this species were examined on six occasions. In all 

 but one of these examinations sporocysts were found. On each 

 occasion a considerable number of the snails were examined with 

 much care, the several organs being teased under a lens. None 

 of the sporocysts, however, were seen in place, in all cases having 

 been found lying at the bottom of the dish in which the snails 

 had been dissected. 



The following extracts from my notes made at the time of 



1 Published by permission of Commissioner of Fisheries. 

 2 Biological Bulletin, 



iq8 



