350 Trematodes Parasitic on British Fishes, [Sess. 



Anthocotyle. Seven species belong to Octohothrium, two to 

 PteroGotyle, and one to each of the other four. In Odo- 

 hothrium the eight posterior suckers are in each of the 

 separate species similar in size and structure, but those of 

 the one species may differ from those of the other. The 

 suckers at the posterior end are arranged four on each side, 

 on or near the lateral margin, except in Octdbothrium lepto- 

 gaster Leuckart. In this species, which is found parasitic 

 on the gills of Ghimcera monstrosa, the distal extremity is 

 considerably expanded, and the eight suckers, which are 

 moderately large, are at the ends of short irregular pro- 

 cesses that spread out into a fan-like shape. The middle 

 portion of the body is elongated and extremely slender. 

 With the exception of one species, all the members of this 

 genus have been obtained on marine fishes. Octobothrium 

 syhillce T. Scott was found on the gills of trout captured 

 in Loch Tay and elsewhere. Octobothrium merlangi is not 

 very rare on the gills of Whiting, and other species occur 

 on Herring and Mackerel. 



Pterocotyle and Dactylocotyle do not differ greatly from 

 Octobothrium. Perhaps one of the more obvious differences 

 is that the posterior suckers are on distinct finger-like stalks. 

 The species are tolerably large, and are found on the gills of 

 Gadoids such as Ling, Cod, and Lythe. 



Phyllocotyle and Plectanocotyle resemble Octobothrium in the 

 arrangement of the posterior suckers, except that the last two 

 of them are small and considerably modified, and situated at 

 the end of a process more or less elongated and narrow, pro- 

 duced by the extension backwards of the apical parts of the 

 body. This process is apparently flexible, and to some extent 

 retractile. Both Phyllocotyle gurnardi and Plectanocotyle lorenzi 

 occur on the gills of the Grey Gurnard {Trigla gurnardus), a 

 species of fish moderately frequent round our coasts. 



In Acanthocotyle merluccii van Beneden & Hesse — ap- 

 parently the only described species of the genus — we find a 

 type distinctly different from Octobothrium. No doubt it has 

 at the posterior end four pairs of cupules or suckers, but the 

 proximal pair are inflated so as to resemble minute bladders, 

 each of which carries hooks; the other three pairs are very 



