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2. À new marine Trematode belonging to the Polystomidae. 
By J.T. Cunningham, Edinburgh. 
. eingeg. 12. Mai 1884, 
I have found this animal, which from the disposition of its 
suckers and the name of its host I have named Stichocotyle Nephropis 
enclosed in cysts in the walls of the intestine of Nephrops norvegicus 
from the Firth of Forth. It is of elongated cylindrical shape, varying 
in size from .75mm to 10mm, according to its age. The most novel 
feature of its structure is a single series of large suckers extending 
down the median ventral line, commencing a little behind the mouth, 
which is near the anterior end, and extending to the posterior end of 
the body. The suckers diminish in size from before backwards, and 
as the animal increases in length additional suckers are formed at the 
posterior end of the series. In small specimens there are only 7 
suckers, in the largest as many as 22. Thus the sucker system ex- 
hibits the characteristics of metameric segmentation, but the metamerism 
does not extend to the other organ-systems which are those of a typical 
Trematode. The intestine is straight and simple without any branches, 
and extends almost to the posterior end of the body terminating blind- 
ly. The main canals of the water-vessel system are relatively of large 
size, and extend from the anterior end of the body to the posterior 
end; there is one on each side of the intestine, and posteriorly the two 
unite behind the intestine in a terminal muscular chamber which ex- 
hibits regular rhythmical pulsations. These lateral canals are crowded 
with large spherical concretions. The terminal chamber opens to the 
exterior by a small dorsal aperture. Ciliated tubules are present on 
the dorsal side of the body above the lateral canals; they probably 
have the same relations as the corresponding structures in other Tre- 
matodes, but I have not yet traced their connections. The generative 
organs are not developed, and I have as yet no evidence as to the way 
in which the parasite reaches its encysted stage in Nephrops, nor as to 
the conditions under which it exists in a state of maturity. This is 
I believe the first case described of one of the Polystomidae passing in 
its development through an encysted condition as an internal parasite. 
The full description of the animal will be published in the Trans- 
actions of the Royal Society of Edinburgh. 
