On Stichocotyle neplnopis CuDiiinnliHiii, a parasite of the American lobster. 475 



adjacent sections shows that the filament in this case ends within 

 a little cavity in the under surface of the cuticula, as shown in the 

 figure, and that there is no connection with the exterior. It seems 

 probable that the nerve fibre grows out from a ganglionic cell toward 

 the exterior, and that when it comes into contact with the cuticula 

 the latter substance becomes dissolved or resorbed over its tip to 

 make a canal by which it may communicate with the exterior. 



Several facts tend to disprove the suggestion that these may be 

 gland cells: they lack the staining qualities characteristic of glands; 

 many of them have two processes extending out from them ; no aper- 

 tures in the cuticula exist in this portion of the body except those 

 already described which are traversed by the hairlike axial filament, 

 a structure not readily explained on the assumption that they are 

 glandular apertures. 



Classification. 



From the description which I have given of this parasite, it will, 

 I think, be sufticieutly evident that it is closely related to the two 

 genera Aspidogaster v. Baer and Cotylogaster Mont. Both the di- 

 gestive and excretory systems give very direct and unmistakable evi- 

 dence of this, as I have already pointed out. The position and ar- 

 rangement of the suckers, as I have previously explained, is also 

 brought, by a study of the method of their origin, into very close 

 agreement with the condition presented by the suckers of those forms. 

 MoxTiCKLLi ('92) has united these two genera, Aspidogaster v. Baer 

 and Cotylogaster Mont., with three others — Platyaspis Mont., 

 Aspidocotyle Die.s. and Macraspis Olsson — whose anatomy is less 

 perfectly known, to form the family of the Aspidobothridae. Monti- 

 CELLi recognized from Cunningham's description the close relationship 

 of Stichocotyle to the other members of this family, but declined to 

 accept it as a separate genus, since only its larval stage was known, 

 and this, from its resemblance to the imperfectly known Macraspis 

 of Olsson, he believed to be the larval condition of that form. In 

 this conclusion I believe him to be in error. One of the grounds on 

 which he bases this opinion is the supposition that Cunningham's 

 drawings represent the suckers of Stichocotyle as being more distinct 

 from one another than they really are. This supposition is supported, 

 he thinks, by his own observations made upon preserved specimens 

 of this worm collected by ilie late 1'. J. Van Beneden. If a certain 



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