LIFE-HISTORY OF BUCEPHALUS HAIMEANUS. 635 
A Study of the Life-history of Bucephalus 
Haimeanus; a Parasite of the Oyster. 
By 
David Hilt Tennent. 
With Plates’ 39—42, 
INTRODUCTION. 
Amone a number of oysters which I procured in February, 
1902, for the purpose of a demonstration, were several which 
were badly infected with the cercaria Bucephalus. At the 
suggestion of Professor Brooks I undertook a study of the 
origin of the germ-cells, from which the cercariz arise, the 
material at my command promising to be favourable for such 
an investigation. 
Nore.—Since I began my studies on the origin of the germ- 
cells in Bucephalus haimeanus two papers on the process 
in related forms have appeared. I refer to those of Reuss 
(41, 1903) on Distomum duplicatum, and of Haswell (28, 
1903) on Kchinostomum sp. Further mention of these papers 
will be made at another place in this paper. 
Economic considerations have also made a study of the 
life history of the parasite of importance. Exact data as to 
the extent of infection, its means of spreading, the effect of 
infection upon the oyster, etc., have been desired. In my 
investigations I have endeavoured to determine not only facts 
of a purely scientific interest, but also those which will be of 
use to the oyster planter. 
