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XVI. — On Stichocotyle Nephropis, a new Trematode. By J. T. Cunningham, 

 B.A., Fellow of University College, Oxford, and Naturalist in charge of 

 the Marine Station, Granton, Edinburgh. (Plate XXXIX.) 



Z. (Read 5th May 1884.) 



The Norway lobster, Nephrops norvegieus, on account of its abundance in 

 the Firth of Forth, and the consequent ease with which it can be obtained from 

 the Newhaven market, is given to the practical classes in the Natural History 

 Laboratory of Edinburgh University for dissection, as an example of the de- 

 capoclous Crustacea. One day in December last, while I was superintending 

 the work of a class engaged in the study of this animal, one of the students, 

 whose name I have unfortunately forgotten, called my attention to some glob- 

 ular protuberances on the intestine of the specimen he was dissecting. At the 

 time I was unable to answer his questions any further than to say that the 

 protuberances were the cysts of a parasite, and I put the specimen by for sub- 

 sequent examination. On opening the cysts afterwards I found in them a 

 small white worm, which proved to be a Trematode possessing novel charac- 

 teristics. In the following paper I shall describe this parasite, and show that 

 it is so distinct from all Trematodes hitherto known as to constitute a new 

 genus. On several occasions I had the pleasure of examining the animal in 

 the company of my friend and former colleague, Mr Duncan Matthews, and 

 some of the points in its structure were first noticed by him. 



I will first describe the animal as completely as possible, and then deal with 

 the manner of its occurrence and its relation to other Trematodes. 



The worms when taken out of the cysts are elongated and cylindrical in 

 shape, one surface, the ventral, being slightly flattened; they vary in length 

 from 75 mm. to 8*0 mm. They are white in colour and somewhat opaque, so 

 that there is considerable difficulty in making out their internal anatomy under 

 the microscope. The body tapers towards each end, the thickest part being 

 near to the oral or anterior extremity. The arrangement of the organs is bi- 

 laterally symmetrical. The mouth is a small simple circular aperture, situated 

 on the ventral surface, close to the anterior end of the body. Behind it, 

 : along the median line of the ventral surface, is a single row of large muscular 

 , suckers, which diminish gradually in size towards the posterior end. The 

 i margins of the mouth are muscular, and its cavity can be dilated and con- 

 tracted, so as to act as an additional sucker. When the animal is viewed with 

 its ventral surface upwards, slightly compressed by a cover-glass, and under a 



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