266 s. GOTO. 



pairs of cliitinous pieces in the posterior sucker of Ph. solece, 

 but this difference can not be regarded as of generic value. I 

 am, moreover, inclined to suspect that the most posterior pair 

 were overlooked by these authors, owing to their exceedingly 

 small size as compared with the other pairs. 



A number of gigantic cells are always associated with 

 the anterior parts of the cliitinous hooks. They are situated 

 strictly symmetrically on either side of the posterior sucker, so that 

 a description of one side will serve for both. As shown in fig. 5, 

 two cells are associated with the most anterior piece and five 

 with the middle piece. They are all of an irregular form, have 

 a coarsely granular protoplasm, and send out processes, which 

 are closely associated with the muscular fibres attached to 

 the chitinous pieces. As the material at my disposal was very 

 old and not sufiiciently well preserved, I could not make out 

 the intimate connection of these protoplasmic processes with the 

 surrounding tissues. But there is no doubt about their close 

 contiguity to the muscular fibres of the chitinous pieces on 

 the one hand and their independence from the network of nerv- 

 ous tissue, which is clearly visible in the sucker and a small por- 

 tion of which is reproduced in fig. 7. In fact the nervous 

 network is situated on a different level in the sucker, being 

 confined more to the deeper layer, while the gigantic cells under 

 consideration are situated close to the ventral surface, just inside 

 the chitinous pieces (fig. 6). In view of these considerations and 

 comparing them with the beautiful results obtained by Betten- 

 dorf ['97] and others on the muscle cells of flat worms I think 

 I am not going much amiss in regarding the cells in question as 

 myoblasts, developed in connection with the strong musculature 

 of the chitinous pieces. I should recommend their further study 



