346 Trematodes Parasitic on British FisJus. [Sess. 



Genus Phyllonella van Beneden & Hesse, 1863. 



Phyllonella solem is a species usually found on the Black 

 Sole (Solea vulgaris) : it has been obtained on Soles captured 

 in the Firth of Clyde and off the Lancashire coast, but does 

 not appear to be very common. It has an ovate outline, and 

 is rather more than a quarter of an inch in length. The 

 large posterior sucker, like that of Upibdella, is not divided 

 into compartments. 



Genus Tristomitm. 



Tristomum molce, sometimes found on the Short Sun-fish, 

 is very thin and flat, and with a nearly circular outline. It 

 is also a tolerably large species, and specimens have been 

 obtained measuring nearly three-fourths of an inch across the 

 longest diameter. The posterior sucker is very large, round, 

 sessile, unarmed, and divided into seven compartments by an 

 equal number of rays ; the rays scarcely reach the centre of 

 the disk. The two rays which bound the sides of the com- 

 partment at the base of the sucker are joined together by a 

 cross-bar ; there is also a central space formed by faint lines 

 joining the inner ends of the seven rays. 



This species was obtained on a Short Sun-fish captured in 

 the Firth of Forth in 1890, and on another captured near 

 Mallaig, west coast of Scotland, in April 1900. 



Couch records Tristoma coccineum Cuv. from the Short 

 Sun-fish, and Yarrell ('British Fishes,' vol. ii. p. 438) gives 

 two figures showing a dorsal and a ventral view of it. Van 

 Beneden suggests that this is not the T. coccineum Cuv. which 

 is found on Xijphias gladius, but is probably Diesing's T. 

 papulosa. 



Genus Trochopus Diesing, 1838. 



Trochopus lineatus T. Scott, 19th Annual Eeport of the 

 Fishery Board for Scotland, Part III., p. 143, PL VIII., 

 fig. 18 (1901). 



This species was obtained in the gill -cavities of Trigla 

 lineata captured in the Clyde. It is a small species, measur- 

 ing only about one-eighth of an inch in length, and is of a 



