The correlation of genera is obvious. Thus, without any doubt 

 Octoplenocotyle is a more .primitive genus than Plectanocotyle. The last 

 genus is very interesting in the fact that it bears only 3 pairs of clamps 

 on the attaching disc, i.e., it ceases development at an earlier stage 



than all other closely related groups. The fact that this is so and that this 

 is not a secondary reduction as in Diclybothriidae is indicated by the 

 absence of traces of the inception of the fourth pair of clamps. It is possible 

 that during careful study of live subjects it will be possible to show that 

 an additional pair of edge hooks, besides those on the outgrowths are pre- 

 served on Plectanocotyle. By its location it will be possible to say definitely 

 which of the pairs of clamps does not develop. As is understandable, it is 

 most probable that it is the fourth pair. 



Vallisiopsis undoubtedly is a secondarily changed genus for it 

 has considerable asymmetry in the structure of the body. It is noteworthy 

 that Chauhan [Chauhan, 1900, (sic date)] refers this genus to Gastro- 

 cotylinae, i.e., likens them with the last Plectanocotylidae, This, as 

 will be seen later, is fully justifiable (see page 468 ). 



4. Family Diclidophoridae Fuhrmann, 1928 p. 431 



(Figs. 54, 86, 87, 101, A, 226, 227, 303-307) 



Choricotylidae Rees and Llewellyn, 1941. 



Discocotylinea having small, middle, and large sizes. The 

 attaching apparatus has 8 chitinous attaching clamps, one pair of edge 

 hooks and one pair of middle hooks. In a number of species the hook 

 armature can be absent (?). The attaching clamps are arranged according 

 to the "discocotylid-type",but their chitinous apparatus consists of 8 

 separate parts. Some of thenn can partially merge with each other forming 

 complexly arranged plates in this manner. For the majority of the genera 

 the asymmetry of the right and left halves of the clamps as a result of 

 the uneven development of the paired chitinous plates is characteristic. 

 Among the adults and apparently among the larvae the eyes are completely 

 absent. The copulatory organ is usually armed with a corona of chitinous 

 hooks. The vaginal ducts are absent for the most part; if they exist they 

 are double or nnore rarely single. The remaining characteristics are 

 similar to those of Mazocraeidae. 



Parasites of marine fishes, Gadiformes (Gadidae), Macuriformes 

 (Macruridae), Perciformes (a number of families) and 



Pleuronectiformes (Bothidae and Pleuronectidae) and Tetrodontiformes 

 (Tetrodontidae). They are also encountered on parasitic isopods. 



Type genus, Diclidophora Diesing, 1850. 



516 



