in the majority of Dactylogyridae (Fig. 5). As a counterpart to such discs 

 could be considered those that are bound together by numerous connecting 

 ridges and which are sharply delineated from the rest of the body, and which 

 are powerfully developed for the sucking action, as in Monocotylidae 

 (Fig. 27) and Capsalidae (Fig. 1). Discs of such a type can be very compli- 

 cated. In them is developed a very complicated series of muscular fibers 



HOImm 



Fig. 23. Microcotyle sp. sp. : A- -M. mugilis 

 Vogt, adult worm from the gills of Mugil 

 auratus Risso from Sebastopol Bay (Black 

 Sea); B--M. gotoi Yamaguti, anterior end of 

 the body (head glands !) of the adult worm 

 from the gills of Hexagrammas octogrammus 

 (Pal. ) from the region of Yablochnoii 

 (Southern Sakhalin, Sea of Japan). 



Fig. 24. Mazocraes alosae 

 Hermann, adult worm from 

 the gills of Alosa caspia 

 (Eichw. ) near the Island of 

 Sara (Caspian Sea). 



which is often completely isolated from the main musculature of the body. 

 The cuticle of the outer edge of such sucking discs forms a very thin 

 membranous margin which is usually entire throughout (for instance 

 Nitzschia.Fig. 17) or cut into festoons (as in Trochopus, Fig. 28). Various 



17 



