642 DAVID HILT TENNENT. 
as having a paired digestion tract, an error which leads 
Diesing (27, 1858) to doubt Siebold’s correct interpretation 
and to form a new genus (Bucephalopsis), to which he 
assigns Lacaze-Duthiers’ B. haimeanus. 
Lacaze-Duthiers (20) describes B. haimeanus and figures 
the sporocysts and cercaria. According to his description 
the mouth is at the anterior end of the body, and a narrow 
cesophageal tube passes backward to the gut. He describes 
the unhealthy appearance of infected oysters, the gonads in 
such oysters having shrunken in size, and the tissues having 
become transparent and watery in appearance. 
Claparéde (28, 1863) obtained B. haimeanus while towing 
in the open sea at Saint Vaast la Hougue. He also found it 
attached to the under side of Sarsia and Oceania. 
Huet (29, 1889) found B. haimeanus in Cardium edule. 
He confirms Lacaze-Duthiers’ observations as to the unhealthy 
appearance of infected specimens, but cannot find the mouth 
and cesophagus described by Duthiers. He says that B. 
haimeanus seems to cause the death of the host, and then 
escapes into the surrounding water. 
McCrady (21), at Charleston, in July, 1868, found several 
oysters in which the gonads were filled with a mass of white 
fibres, the germ tubes of a Bucephalus. Concerning these 
fibres McCrady says: “The impression left upon me by the 
distinct resistance to the knife was that they would prove 
chitinous.”? Consequently, on account of this rigidity of the 
tubes, he describes the cercaria which he found as a new 
species, B. cuculus. He mentions the tail as bristling 
with cells like lasso cells. He has “no recollection” of a 
ventral aperture or sucker, and saw none of the regularity 
of construction of the body such as was observed by Lacaze- 
Duthiers. 
In infected oysters the gonad was covered bya transparent 
skin, through which the branching tubes might be seen. 
Parasites were found only in the gonads, and in infected 
oysters there was no trace of spermatozoa or eggs. 
