the clamps. At the same time, in Cemocotyle the asymmetry of the disc is also observed: 

 One edge bears a sm.all number of typical clamps, whereas the second- -approximately the 

 same quantity of typical ones and in addition to that a considerable number of metamorphosed 

 ones. One must also note that Pyragraphorus is closer to Microcotyle both by the absence 

 of chitinous hooks as well as by the interior structure, whereas Cemocotyle is somewhat 

 further removed because it has 3 pairs of typical hooks on the posterior end in the adult 

 state, that is, it retains more primitive traits. 



In certain relations, the genus Cemocotyle is close to Heteraxine which, how- 

 ever, has no chitinous hooks in the adult state. The last genus is undoubtedly very close to 

 Microcotyle , _s^ str. and differs basically by the asymmetry of the disc (not clamps!) which 

 on one side bears a very small, and on the other a considerable number of clamps. 



The genus Diplasiocotyle, material of which we did not have, is very odd. 

 Judging by the description of Sandars (Sandars, 1944a)l, this 



Cited according to Sproston .because we did not see the present work. 



genus has a symmetrical disc equipped with a small number of clamps of 

 distinctly different sizes. Thus, the first, (posterior) pair of clamps has 

 the sizes of 0. 062 x 0. 044 mm whereas the size of the remaining pair 

 fluctuates from 0. 250 x 0. 187 to 0. 437 x 0. 312 mm. One can suppose that 

 a similar development of clamps is connected with certain peculiarities of 

 attachment during the early stages of the development of the worms. The 

 interior structure of the only species of this genus is apparently very close 

 to Microcotyle, s. str. The author describes 2 "suckers" on the dorsal side 

 of the body but does not indicate their connections with the vaginal ducts 

 which probably takes place. Certain peculiarities of the development of 

 Diplasiocotyle (see page 216) speak for a considerable specialization of 

 this genus. 



The asymmetry of the disc of Microcotylidae, about which we 

 have often spoken, arises in all preceding genera at the irregular or un- 

 even development of its right and left halves depending on changes in the 

 number of clamps located on it. With this the clamps themselves lying on 

 both halves of the disc, are either completely alike or mirrored to each 

 other, and the sizes of the clamps on both sides do not differ from each 

 other. In contrast to this there are two more types of asymmetry of the p. 443 



disc in Microcotylidae: 1) by way of the fornaation on one side of large and on 

 the other side of small clamps; 2) by means of "unfolding" of both rows of 

 clamps into one line in such a way that the posterior end of the disc of the 

 larva is in the middle of one continuous row of clamps lying at a more or 

 less sharp angle to the longitudinal axis of the body of the animal. The 



530 



