The disposition on the disc of these attaching formations is 

 not uniform. In the free -swimming larvae the edge hooks, which lie 

 along the edge of the disc with their points facing the ventral side, retain 

 their location, with the exception of the first rwo pairs which unfold and 

 lie with their edges toward the dorsal side. This disposition of edge 

 hooks persists during their entire life among worms of this genus. The 

 large pair of middle hooks, i.e., first from the point of view of time of 

 inception is located on the ventral side but is oriented with its points to- 

 ward the dorsal side, whereas the smaller pair, which is closer to the 

 dorsal side, conversly faces the ventral side with its points. The unpaired 

 middle connecting plate is incepted and lies on the ventral side. The 

 following stage of development of L. elegans (Fig. 186) is characterized p. 169 

 by the appearance of inceptions of the paired connecting plates. They 

 appear on the dorsal side along the edges of the middle plate and have the 

 shape of straight sticks, sharpened toward the middle line of the disc, 

 and slightly widening toward the opposite end. They are incepted in the 

 interior of the parenchyma of the disc without touching the chitinous 

 elements on either side. During this stage of development the length of 

 worms is about 0. 08 mm whereas the width is about 0. 035 mm; the 

 attaching disc is about 0. 045 mm in width. 



ftO/wM 



Fig. 186. Lamellodiscus 

 elegans Bychowsky, young 

 worm from the gills of 

 Sargus annularis from the 

 region of Karadaga (Black 

 Sea). 



Fig. 187. Lamellodiscus elegans 

 Bychowsky, attaching armature of the 

 disc of developing worms from the 

 gills of Sargus annularis (L,. ) from the 

 region of Karadaga (Black Sea). 

 Explanation in text. 



182 



