1911] Watson: The Genus Gyrocotyle. 359 



Mollusken, namlich der Mactra edulis stammt, so i*t es sehr wahr- 

 scheinlirli, dnss aueh die von Grube und Wagener beschriebene 

 Art ihren eigentlichen Wohnort aicht in der Chimaera mon- 

 strosa, sondern vielmehr in einer jener Mollusken, deren Frag- 

 mente sich im Darme des Fisches verfanden, habe." 



Van I !i -nrilcii and Hesse 1864), maintain the two genera and 

 refer both to the Hirudinea as the "Malaeobdellaria dioiei." 

 These authors agreed with Diesing in regarcltng a mollusk as the 

 true host of Amphipl i/clus, stating expliuitly that it is not to be 

 considered a parasite of Chimaera, but as having been taken in 

 by ehanee with the mollusk on which the fish feeds. Later Van 

 Beneden (1869) withdrew from this position and classed Amphi- 

 ptyches as a true parasite of Chimaera. 



No further work was done on either of these forms until 

 Monticelli's "Saggio di una morfologia dei trematodi" (1888) in 

 which he excludes Gyrocotyle and Amphiptyches from the 

 trematodes, referring Gyrocotylt to the bdellodes, near Malacob- 

 della, following Hesse and Van Beneden. He affiliates Amphi- 

 ptyches with the cestodes, suggesting that AmphUina and Amphi- 

 ptyches are closely related forms, the latter being the simpler of 

 the two, and together should be regarded as forms transitional 

 between trematodes and cestodes. Shortly after this Jfonticelli 

 (1889b) compared the specimens of Gyrocotyh and Amphi- 

 ptyches available in the museums of Leipzig, Berlin and Vienna. 

 As a result of the comparison he says : 



" Io ho potuto stabilire eon eertezza fa foro posizione sistematica 



desumendola dai loro caratteri anatomiei ed embrrologici. Dalle mie 

 recerehe sono pervenuto afle seguenti concfusioni : 



" 1. Che 1' Amphiptyches ed il Gyrococtyle devono eonsiderarsi, come gia 



pensavano il Wagener ed il Diesing, due specie distinte def gen. Gyro- 



cotyle. Le due specie si ehiameranno: G. rugosa Diesing e G. urna Grube 

 e Wiener. 



"2. <'he il gen. Gyrocotyle deve allogarsi fra i Cestodi e riguardarsi 

 affine all' AmphUina." 



He goes on to say that the first conclusion rests on remarkable 

 uniformity of structure; the sole external difference being the 

 lack or slight development of the lateral folds in Gyrocotyh . 

 The second conclusion rests on the mode of development and 

 internal structure of both species. The similarity of eestodarian 



