THE TREMATODE PARASITES OF FISHES. 491 



Prosorhynchus respectively. Bucephalinae includes the genera Buce- 

 fhalus, as type, Bucephalopsis and Rhipidocotyle. 



The definition of these three genera may be summed up briefly as 

 follows : — 



Bucephalus Baer, 1827. 



Bucephalinae in which the anterior end is provided with a muscular 

 sucker around which are a number of muscular retractile tentacles or 

 fimbriae. Type : B. polyniorphus Baer, 1827 {—Gasterostomum fimhria- 

 tum V. Siebold, 1848) B. minimus (Stossich) {Gasterostomum, minimum 

 Stossich, 1887, nee. Wagener, 1852) may also be included in this genus. 



Gasterostomum gorgon Linton, 1905, may be provisionally included 

 here, but will probably require to be regarded as the type of a distinct 

 genus. The " Gasterostomum sp." depicted by Linton (1910, Fig. 225) 

 from Sphyraena barracuda may possibly belong to this genus. 



Bucephalopsis Diesing, 1855. 



Bucephalinae in which the anterior end is provided with a simple 

 globular muscular sucker. Type : B. gracilescens (Rud., 1819). G. 

 tergestinum Stossich, 1883, should be included here, and probably a 

 number of American forms. 



Rhipidocotyle Diesing, 1858. 



Bucephalinae in which the anterior end is provided with a feebly 

 developed, shallow sucker surmounted by a fan-shaped hood. When this 

 is contracted the anterior end appears square. Type : R. minima 

 (Wagener, 1852), Nicoll, 1914 { = Gasterostomum triglae van Ben., 1870, 

 Nicoll, 1909), includes also R. viperae (van Ben., 1870), Nicoll, 1914, and 

 probably a number of species from American fishes (Linton, 1910, 

 Figs. 217, 222, 223). 



Family BUCEPHALIDAE. 



Sub-Family Bucephalinae. 



Genus BUCEPHALOPSIS (Diesing). 



Bucephalopsis gracilescens (End.). 



Lebour, 1908, pp. 18-21. 



This common parasite of Lophius piscatorius was found in four out of 

 five specimens of that fish. It occurred in the intestine and pyloric 

 caeca, usually in large numbers. 



