27. The development of Microcotyle Beneden and Hesse 



p. 204 



The genus Microcotyle is characterized by a powerful develop- 

 ment of the attaching disc on which is located a considerable number of 

 pairs of attaching clamps of the same shape .lying nnore or less synnmietri- 

 cally in relation to the long axis of the disc. Altogether, 6 species of 

 Microcotyle have been studied with varying degrees of completeness, of 

 which three were studied by us, one by our collaborator, U. A. Strelkov, 

 one by Remley (Remley, 1936, 1942) and finally one by Sproston (Sproston, 

 1946). Because of the fact that the genus Microcotyle undoubtedly is very 

 artificial and during subsequent works will probably be subdivided into a 

 number of smaller genera, we considered it more convenient to express the 



existing data on each species sepa- 

 rately, beginning with the data of 

 Remley. 



Microcotyle spinicirrus 

 MacCallum--is a parasite of the 

 North American fresh-water fish, 

 Aplodinotus grunniens Raf. (Fam. 

 Sciaenidae), the development of 

 which was studied by Remley. 

 Adult worms (Fig. 235), which reach 

 up to 13 mm in length, are dis- 



Fig. 235. Microcotyle spinicirrus Fig. 236. Microcotyle spinicirrus 



MacCallumi, adult worm. (Accord- 

 ing to Remley, 1942), 



MacCallum, free -swimming larva. 

 (According to Remley, 1942). 



tinguished by a powerful development of the attaching disc which is located 

 completely behind the body so. that the last testes lie anterior to its be- 

 binning. The number of attaching clamps is very large, up to 50 on each 

 side. The free-swimming larva which has just emerged from the egg of 

 M. spinicirrus is 0. 23 mm in length and 0. 1 mm in width (Fig. 236). It 

 is flattened dorsoventrally and has a more or less oval form. The ciliary 

 covering is represented by three zones of ciliary epithelium along the 



222 



