The process of formation of sex ducts has been poorly studied. The 

 appended figures give certain notions about it (Figs. 238, 239). 



Microcotyle mugilis Vogt (Fig. 23)--It is a common parasite 

 of Black Sea gray mullets (Mugis sp. sp. ) and is characterized, just as 

 the preceding species, by the disc, located behind the body but its number 

 of clamps is considerably smaller- -up to 30 on each side. We obtained 

 the development of this worm at the Sebastopol Biological Station in 1935, 

 but unfortunately the larvae which had already been formed and which 

 moved vigorously inside the eggs could not emerge and perished because 

 of a powerful growth of microscopic weeds and bacteria around the egg. 

 We took them out of the eggs in somewhat damaged condition and because 

 of that we cannot give detailed information about the sizes of the larvae 

 and their ciliary covering. The larva has a well-developed pigmented 

 eye, a rounded pharynx and a sac-shaped intestine. The attaching disc 

 (Fig. 240) is equipped with 10 edge hooks, 2 pairs of middle hooks, p. 207 



and one pair of attaching clamps. If one takes into consideration 

 therefore, that these clamps are incepted at the place of the edge hooks 

 during their transformation the nature of the armature corresponds to 



that of M. spinicirrus Remley. The structure of the edge hooks is the 

 same as among this type while the middle hooks have a somewhat different 

 structure. The first pair of middle hooks strongly resemble the large 

 middle hooks of Discocotyle and Diplozoon in shape. They consist of 

 two parts: a hook with the base widened at the top and with a rather 

 strong point and of a thin, long chitinous little stick which joins with the 

 interior angle of the upper part of the base. The 2nd pair has powerful 

 hook parts and a more weakly developed handle. The transversal off- 

 shoot between thenn is developed rather strongly which makes their shape 

 resemble the edge hooks . On the other hand these hooks, as is evident 

 from M. spinicirrus Remley, can be likened to the usual ones and then (one 

 may, nobis) speak about a more powerfully developed extension of the 

 middle hooks. The pair of attaching clamps is developed very distinctly 

 and already has all the same chitinous parts as the clamps of the other 

 individuals. The sizes of the edge hooks are about 0.014 - 0.016 mm, 

 of the 1st pair of middle hooks--0. 05, of the 2nd pair--0, 03 mm; 

 the attaching clamps are 0. 025 mm with a width of 0. 04 mm. We did not 

 obtain any stages intermediate between the mature individuals and the 

 free -swimming larva. 



Microcotyle pomatomi Goto (Fig. 241)--A parasite of Black 

 Sea Bluefish -- Pomatomus saltatrix (L. ), has a structure resembling 

 the two preceding species but with a more powerful attaching disc on 

 which lie from 90 to 100 pairs of clamps than among M. spinicirrus 

 Remley. In contrast to the preceding species this Microcotyle has 

 numerous chitinous thorns in the sex cloaca and not a crown of large 

 thorns on the copulatory organ. During his work at the Sebastopol 



225 



