326 BULLETIN OF THE BUREAU OF FISHERIES. 



to the genus Rhynchobothrium, one species w;is of very frequent occurrence, having 

 been found in 15 different fishes. Doubtless some of the finds, in which the pro- 

 boscides were not seen extended, also belong to this species, which is usually 

 characterized in these notes as being small, with relatively lone- hooks, suggesting, 

 indeed. R. longispiht Linton (figs. 87-93). 



Otdbothrvum crenacolli Linton, recorded in my Woods Hole papers as adult only, 

 in Sphyrna tygsena, was found .encysted in 14 different Beaufort fishes. It is quite 

 evident that this form is encysted in the fishes of Woods Hole also. Rhynchobothrium 

 sp.. from Rhombus triacanthus (Parasites of Fishes of the Woods Hole Region, pp. 

 453—454. figs. 255-265) is really Otobothrium crenacolle. 



Identification of the Tetrarhynchidae is difficult unless the proboscides can he 

 seen. It is better, indeed, that the proboscides be completely everted, since differ- 

 ences in the size and arrangement of the hooks in some species are often very 

 considerable in different parts of the proboscis. But little can lie determined rela- 

 tive to the arrangement of the hooks on the inverted proboscis. 



At least two species of the genus Synbothrium are represented: S.filicolle Linton, 

 neck of scolex elongated, slender; hooks, at least those at the base of the proboscis, 

 slender and spine-like. Synbothrium sp., scolex relatively stout; books of several 

 different sizes and forms, but all more or less recurved. (Figs. 116—1181) 



The latter appears to be near the larval form referred in a former paper to 

 Tetrarhynohus erinaceus Beneden (Proceedings U. S. National Museum, vol. xix, 

 1898, pp. 811-812, jil. i.xvii. figs. 1-8), which belongs in the genus Synbothrium.. 



The larval cestodes, doubtless representing several different genera, recorded in 

 Parasites of the Woods Hole Region under the name Scolex polymorphous, were found 

 in 34 of the 59 Beaufort fishes examined (figs. 7ti-7'.'). 



As at Woods Hole, these forms are found not only in the alimentary tracts of 

 their hosts, but also in the cystic ducts of several. They are almost never absent 

 from the cystic duct of Oynmcion regalis. In all cases where these worms have been 

 obtained from the cystic duct and from the intestine of the same fish, those coming 

 from the cystic duct arc larger, plumper, and rnosre opaque than those from the 

 intestine. Some of the older larvae suggested the genera Calliobothrium, Acamtho- 

 bothrium, and Phort iobothrium. 



One interesting cyst may be adverted to here (tig. 115) as furnishing an example 

 of the absorption of an encysted larva. The cyst contains two bunches of hooks, 

 which represent all that is left of a larval cestode, probably Tetrarhynohus bisulcatus. 



TKEMATODA. 



It has been thought best to retain the generic name Distomum (see Bulletin of 

 the V . S. Fish Commission for 1899, p. 408). Respecting the classification of the 

 distomes, the author is aware that his papers should be brought into some sort of 

 harmony with the nomenclature of Loos. Lube. Pratt. Stiles, and others. An 

 attempt indeed was made to refer some of the new forms to genera into which the 

 old genus Distomum has been broken up. but the result was not altogether satisfac- 

 tory, in that it seemed to necessitate the creation of still other new genera, which, in 

 view of the small number of specimens in many cases, ami their poor condition, or 

 immaturity in others, seemed to me to lie an undesirable thing to do. 



