McCrady] 176 Ll^ec. 3, 



Bucephalus euculus nov. spec. 



In total ignorance of the observations of von Baer npoii Bucepha- 

 lus polymorphic, and of those of Laeaze-Duthiers upon Bucephalus 

 Haimeanus. or that Claparede had observed what was probably an 

 advanced freely swimming stage of the latter species, in July, 1868, 

 I found in the oysters of Charleston a closely allied entozoon. My 

 observations, though not sufficiently detailed to be of any great inter- 

 est, nevertheless probably indicate at least a new species, and are, I 

 believe, the first record of this remarkable entozoon in America. 



On the 23d of July (1868), I examined six oysters as to the con- 

 dition of their reproductive organs. My journal records that only 

 one of them was in egg; two others being plentifully supplied with 

 spermatozoa; while the remaining three, including the largest, had 

 their reproductive organs filled in every direction with a peculiar par- 

 asitic growth. As soon as I opened the organ I was struck with the 

 white fibres brought up by the knife, as something I had never seen 

 before. With the microscope I soon ascertained the presence of 

 various stages of the development of a vermiform larva, provided in 

 its most advanced form with two long tentaculiform organs at one 

 extremity, the portion to which they were attached being distin- 

 guished from the rest of the body by a marked constriction. The 

 cavity within the body was very evident, but no evidence could be 

 obtained that even in the most advanced form it extended to either 

 extremity. The part bearing the tentacula was not only separated 

 by a marked constriction from the body, but seemed to be provided 

 with lip-like folds, such as frequently appear at the oral extremity of 

 the gastrostyle of a Hyclroid Medusa. The opposite extremity of 

 the body was truncated, and I observed some appearances which I 

 thought might be due to the animal's attaching itself by this trun- 

 cated extremity, and behaving like a hydroid larva, lengthening and 

 shortening its body, the lower parts of which could be considerably 

 elongated. 



Bound embryos, like the outline, fig. 1, were observed, but in this 

 instance these were detached from the others, and it could only be 

 surmised that they really were the youngest stage of'the same ani- 

 mal. The outlines 2, 3, 4, and 5, and one representing the same 

 stage as fig. 6, were satisfactorily traceable to the cysts, where they 

 were observed to be enclosed usually three in the same cyst. 



Six days after (July 29), I found another oyster infested by the 

 same parasite; my notes represent the generative organ as filled with 



