210 



ACTINIARIA 



In the specimens i, 3, 4, 5 I have found solitary typical nematocysts in the actinopharynx. They 

 were a little larger (29 38 X 2,5 p) than usual. Whether these nematocysts belong to the actinopharynx 

 or are sticking to it, I cannot with certainty decide, in specimen 5 I observed only a few typical nematocysts 

 in the maceration preparations, in the other specimens the nematocysts, put down in the table, were, how- 

 ever, numerous. The mesogloeal, longitudinal muscles of the tentacles on transverse sections show meshes 

 of ordinary size, which are situated now in the middle of the mesogloea, now nearer to the endoderm. In the 

 textfig. 198 I have reproduced a transverse section of a tentacle ; the muscles are weaker on the outer side 



than on the inner one. The radial mus- 

 cles of the oral disc recall the longitud- 

 inal muscles of the tentacles. They are 

 the best developed in the specimens i 

 and 5 (textfig. 199). They are distinctly 

 interrupted at the insertions of the me- 

 senteries. 



The number of mesenteries varies. 

 In one half of specimen i with 96 tentacles 

 I counted 54 pairs of mesenteries (27 

 pairs sterile and as many fertile) , in spe- 

 cimen 2 with 90 tentacles the pairs of 

 mesenteries were 94 (22 on one side and 

 Fig. 198 Fig. 199 25 on the other, sterile and as many fer- 



Textfigs. 198 199. Parasicyonis sarsii. 



Transverse sections of tentacle (fig. 198) and of oral disc (fig. 199). 



tile) , in specimen 4 with 62 tentacles pro- 

 bably 90 pairs of mesenteries half of which 



sterile, in the specimen 5 with 86 tentacles 86 (18 pairs on one side and 25 on the other, sterile and 

 as many fertile). As we see, the arrangement of the mesenteries was different on both sides of the 

 directive plane. In one half of specimen i the mesenteries of the first to the third cycles were perfect, 

 among the mesenteries of the fourth cycle three pairs reached the actinopharynx, six pairs consisted of a per- 

 fect and an imperfect mesentery and three pairs were imperfect like the mesenteries of the fifth and sixth 

 orders. In specimen 4 there were in the whole animal probably 26 pairs perfect and three pairs consisted of 

 a perfect and an imperfect mesentery. In specimen 5 I observed on the less developed side eleven pairs 

 perfect and three consisting of a perfect and an imperfect mesentery, on the other side probably thirteen pairs 

 perfect and four pairs consisting of a perfect and an imperfect mesentery. The pairs, showing a different develop- 

 ment of both their mesenteries are, as far as I can see, irregularly arranged. Half the mesenteries are sterile, the 

 other half fertile, the latter are the younger and have well-developed filaments with ciliated streaks like the 

 other mesenteries, but never reach the distal part of the column. 



The longitudinal muscles of the mesenteries are rather weak and hardly show any distinct pennons. 

 The parietobasilar muscles are broad and reach far upwards, but consist of a non folded muscle lamella. Oral 

 stomata are present. In two specimens I have also observed marginal stomata, but they do not seem to be 

 constant. The ciliated streaks are well developed. 



