one unpaired connecting plate (of the second pair of middle hooks), two 

 connecting plates of the first pair of middle hooks and a pair of supple- 

 mentary plates, articulating with the body of the second pair of middle p. 163 

 hooks; the edge hooks are of two types; 4 pairs of small ones which pre- 

 serve embryonic shapes and sizes and three pairs of large ones with 

 massive handles. A. V. Gussew in his work on Monogenoidea of the 

 fishes of L,ake Hanka (1955) describes a free-swimming larva in one of 

 the latter stages of development of B. pseudobagri Achmerow. The 

 development in the eggs takes place in four days at temperatures of 

 16 - 21°, The larva which has just emerged from the egg is torpedo- 

 shaped with 3 zones of cilia located just as among Dactylogyrus (Fig. 176). 

 Gussew succeeded in counting, approximately, the number of cells in 

 each of the ciliary zones. Thus, the first zone consists of 9 + 9 (the very p. 164 

 anterior end of the body of the larva is free of ciliary cells), the middle 

 of 6 + 6 (can be 7 + 7) and finally the posterior, unpaired and lying in the 

 shape of a little cap on the dorsal side behind the disc --of 12(?) ciliary 

 cells. The larva (is equipped, nobis) with 4 well-developed eyes. The 

 attaching disc (Fig. 177) is equipped only with 7 pairs of edge hooks, 0. 013 - 

 0.017 mm in length. There are no traces of other armature. In addition 

 to that, Gussew writes in his work: "Besides the mature worms we found 

 one young specimen of this type in which the ventral middle hooks (the first 

 pair according to our ternninology--B. B. ) were almost formed (their 

 length is 0. 027 min, the length of the point is 0. 013 mm), their connecting 

 plates are yet without articulated little heads (their length is 0. 027, their 



D.DIhh 



Fig. 177. Bychowskyella pseudo - 

 bagri Achmerow, attaching arma- 

 ture of a free -swimming larva. 



I10IHM_ 



Fig. 178. Bychowskyella pseudo- 

 bagri Achmerow, attaching arma- 

 ture of the young worm in the pro- 

 cess of development. Pseudobagrus 

 fulvidraco (Rich. ). (According to 

 Gussew, 1955). 



thickness is 0.003 mm), the dorsal middle hooks (second pair--B.B. ) are 

 as yet without a body, and are represented only by the point and its 

 narrowed part, whereas their connecting plate is in the shape of a tender. 



176 



