easily see that the younger pairs have considerably smaller sizes on an 

 individual in the process of development which as yet does not have a full 

 number of clamps. The inception of each pair takes place simultaneously, 

 although in rare cases we happened to observe the inception of one clamp 

 somewhat earlier than the other (clamp of the same pair, nobis). 



23. The development of Octostoma Kuhn (= Kuhnia Sproston) 



During our work in southern Sakhalin in August-September, 

 1946, we obtained the free-swimming larvae of ^. scombri Kuhn. 

 Approximately at the same time, the larvae of this species were obtained 

 from European herring by Gallien and Calvez (Gallien and Calvez, 1947),. 

 Adult forms of Octostoma (Fig. 25) are similar in the structure of the 



p. 197 



Fig. 224. Octostoma scombri Kuhn, free -swimming larva. 



attaching apparatus to Mazocraes, differing by a somewhat large develop- 

 ment of their chitinous parts. According to our data the free-swimming 

 larva (Fig. 224) is spindle-shaped with rounded ends and the greatest 

 width is in the middle of the body. The length of the body of the larva is 

 about 0. 23 to 0. 26 mm when the width is 0. 08 - 0. 1 mm. At first the 

 attaching disc is delineated from the body rather weakly but soon unfolds 

 and then extends laterally beyond the general contour of the body. Behind 



214 



