30 
this is not so, but when he gives among the examples G. gran- 
lescens, Wagener, and G. armatum, Molin, it is difficult to agree 
with him, for here we have two really different forms, so different 
that Odhner has instituted a new genus {Prosorhynchus) for the 
latter and its allies. I am more inclined to think that G. graci- 
lescens, which is so abundant on this coast, and his Gasterostomum 
from the Gar Tylosurus marinus are different species and not 
physiological varieties, and although Dr. Tennant has practically 
proved by most interesting experiments that the American Buce- 
phalus from the oyster is the larval form of his Gasterostomum and 
the intermediate host is the Silverside Menidia menidia, I do not 
think we can yet say with certainty that the Bucephalus from the 
American oyster is the same species as the British form, although 
they are much alike. The difference in size of the Gasterostomum 
from the Gar (1 mm.) and that from the Angler (6 mm.) is great. 
The vitellaria in the former occur in roundish clusters at the 
anterior end of the worm just behind the anterior sucker, whilst 
those in the latter are always in strings down the sides, reaching 
from the anterior end to beyond the intestine. The British form 
is altogether more elongated than the form Dr. Tennant describes 
The second stage of G. gracilescens is found encysted m the 
nerves of various gadoid fishes. The nerves are much swollen out, 
each swelling being a cyst containing a Trematode. These are the 
« Bodies of Munro » found by Maddox* to be encysted Trematodes, 
and identified by him with G. gracilescens. No proofs have yet 
been given, but there seems little doubt that these worms from the 
nerves are the immature G. gracilescens. Olsson t found these 
cysts in the brains and nerves of several gadoids, and he also reiers 
them to G. gracilescens. It is very common on this coast m the 
nerves of the Haddock, Cod and Whiting. It is most abundant in 
the Haddock, every specimen so far examined being infested along 
the spinal nerves, especially near the tail where they are crowded 
together, and also in the nerves of the brain, particularly the 
auditory nerve. In the Cod it is also common, but here it is not 
so often in the spinal nerves but frequently in the ear itself, where 
the capsules are seen attached to the thin membrane lining the 
auditory sac, and are also free in the fluid which fills the cavity. 
In the same position it is sometimes to be found m the Whiting, 
*Maddox, R. I 
Common Haddock. 1 
t Olsson, op. cit., page 51. 
L., "Some Remarks on the Parasites found in the Norves etc., of the 
." Journal of Microscopical Science, vol. 7, N.b., page r* l^oo'V- 
