LIFE-HISTORY OF BUCEPHALUS HAIMEANUS. 675 
the gills and viscera with the naked eye no parasites of the 
Gasterostomum type could be seen. After slitting open the 
stomach and intestine and spreading it out upon.a glass plate 
I carefully washed the contents free from the walls with sea- 
water. Examining these washings with a magnification of 
about 150 diameters I found present, besides numbers of 
cestode larva, great numbers of small transparent cysts of 
the appearance shown in fig. 48, as well as undoubted Gas- 
terostomum forms like those shown in fig. 49. 
The encysted forms were surrounded by arather transparent 
capsule through which the structure of the enclosed form 
could be seen. 
The free forms were but slightly different in appearance 
from Bucephali which have lost their tails. But I had no 
proof, as yet, that these forms were related to the forms found 
in the gar. While there was a general resemblance between 
the two I did not feel justified in concluding that the one 
developed to the other. 
Recourse was had to further feeding experiments. 
Experiments for determining the relationship 
between the Gasterostomum found in the 
Silverside and the Gasterostomum found in 
the Gar. 
As a further experiment I decided upon feeding the 
viscera of the Silversides to fish in which Gasterostomum 
did not normally occur as a parasite. For this purpose I 
selected four species of fish, the white perch (Morone 
americana), black bass (Centropristis striatus), 
croaker (Micropogon undulatus), and pin-fish (Lagodon 
rhomboides). 
Each species was placed in a separate aquarium. The 
experiment lasted a week, during which, on alternate days, 
I fed the fish, viscera from the Silverside, giving no other 
food, | 
