1910-1911.] Trematodes Parasitic on British Fishes. 347 



somewhat broadly-oval shape. The posterior sucker is large 

 and circular ; on the under side of it twelve distinct rays are 

 seen, extending at nearly regular intervals from the margin 

 towards the centre. The two posterior rays have their inner 

 ends apparently free, but those of the other ten rays are 

 joined to a central, nearly circular, ring. The ray on each 

 side of the two posterior rays referred to is furnished 

 with a small hook. This species is provided with four 

 distinct eyes. 



Trochopus diplacanthus Massa, " Contribute alio studio del 

 genere Trochopus — Nota prelim, reassuntiva," ' Monit. z. Ital.,' 

 Anno 14, pag. 252 (1903). 



This species has been found by my son, Mr A. Scott, at- 

 tached to the gills of Yellow Gurnards {Trigla hirundo) 

 captured off the Lancashire coast. It differs from T. lineatus 

 in the number and arrangement of the rays in the large 

 posterior sucker. 



Genus Thaumatocotyle T. Scott, 1904. 



Thaumatocotyle concinna T. Scott, 22nd Annual Eeport of 

 the Fishery Board for Scotland, Part III., p. 278, PL XVII., 



fig- 1^- . . 



In this species the large posterior sucker is divided into 

 thirteen marginal compartments, separated from each other 

 by narrow muscular bands. The body is narrow and elon- 

 gated, and it is slightly bifurcated at the anterior end. It 

 is a small species (about three mm. in length), and easily 

 overlooked. It was obtained in the nostrils of a Trygon 

 pastinaca captured in the Dornoch Firth in October 1905. 



Genus Acanthocotyle Monticelli, 1888. 



Acanthocotyle monticellii T. Scott, 20th Annual Report of 

 the Fishery Board for Scotland, Part III., p. 300, PL XIII., 

 figs. 31-33. 



This species belongs to a genus peculiar among the Tristo- 

 matidse because of the structure of the posterior sucker. This 

 sucker is large and of a circular form ; it is furnished with 

 numerous rows of small teeth, which extend like radii from 



