The powerful development of the secondary attaching disc on 

 which are located a considerable number of peculiar cuticular thorns lying 

 in regular radial rows is characteristic for Acanthocotyle, The primary 

 attaching disc lies at the posterior edge of the secondary disc and is 

 characterized by very weak development. An impression is created that 

 either it does not grow at all or alnriost does not grow after the settling of 

 the larva on the skin of the host just as its edge and middle hooks apparently 

 do not grow. 



Apparently the same peculiarities of the prinnary disc are also 

 characteristic for Lophocotyle. As regards this genus, it differs fronn 

 Acanthocotyle by a number of very substantial characteristics, part of 

 which are fully authentic and part of which arouse doubt, just as does the 

 finding of the single species on Nototheniidae as was indicated before 

 (page 275 ). One must refer the presence of the chitinous pipe of the 

 copulatory organ, which is completely absent among Acanthocotyle, to the 

 authentic differences. This characteristic, i.e., the presence of the 



pipe, undoubtedly is peculiar to forms more primitive in structure and 

 hence Lophocotyle can be considered as closer to the ancestral genera 

 than to Acanthocotyle. The location of the opening of the uterus not on the 

 side of the body but on its ventral surface is not less important, and also 

 a more primitive characteristic of Lophocotyle. We consider the absence 

 of chitinous thorns on the secondary disc of Lophocotyle to be the most 

 important unsubstantiated characteristic. It is doubtful that during the 

 process of evolution their appearance was sudden, it is more likely that p. 385 



they developed from cuticular formations analogous and perhaps homologous i 



to the ones among Diplectanidae. In addition to that, the secondary disc of \ 



Acanthocotylinae generally resembles the supplementary discs of the ' 



representatives of this family very much, both by its place of inception and 

 by the characteristics of its "thorns, " We cannot say now whether this 

 similarity appears as a result of a common origin or whether here takes 

 place a coarse convergence, because of insufficient material to make J 



authentic conclusions, but later it will be necessary to give the most 

 meticulous attention to this sinailarity (see page 466 ). Returning to the 

 absence of thorns along the disc of Lophocotyle, we think it probable that \ 



they are absent as a result of improper fixation of both examples known at : 



the present time, which is noticed by the author of the species himself i 



(Braun, 1896) and by Price (Price, 1938a). In any case this question de- j 



mands re -examination. As regards the nature of the septa of the secondary ' 



disc of Lophocotyle, they are not described clearly enough to permit the 

 formulation of any basic conclusions on the subject. On the whole, in 

 spite of all the shortcomings of the description there is no doubt that the 

 genus Lophocotyle is very close to Acanthocotyle and is more primitive. 



460 



