2l8 



ACTINIARIA 



S. tuberculata, wherefore the tentacle-lacking part of the oral disc is large. The actinopharynx is of ordinary 

 length. In the other exterior characters this species agrees with S. tuberculata. 



Anatomical description: The interior organisation also much recalls that of S. tuberculata. 

 The nematocysts are, however, larger, especially those of the tentacles. The ectoderm of the column contains 

 rather numerous nematocysts, 17 — 22 X 2 ;« in size. In the tentacles they reach a size of 36 — 41 X 2,5 ^ 

 ^ 1 ^ andinthe actinopharynx 29 — 36(38) x about 3/1. I have in the actino- 



pharynx also observed some nematocysts with discernible basal part 

 to the spiral thread. They are 26 — 29 X 5 // in size. The spirocysts 

 of the tentacles vary from 24 X 2 a to 62 X 4 ji. 



The arrangement of the mesenteries mostly agrees with that 

 of specimen 4 of 5. tuberculata. A schematic figure of the arrange- 

 ment of the stronger mesenteries I have given in textfig. 203. The 

 agroupment of the mesenteries in both the uppermost sextants does 

 not completely correspond with that of 5. tuberculata nor with that 

 of the middle sextants. The perfect pairs are, however, 16, three 

 pairs consist of one imperfect and one perfect mesentery. Both 

 mesenteries of the imperfect pairs do not differ so much in size as the 

 former species. I have been able to determine with certainty the 

 position of the mesenteries of the first cycle (on the figure 

 designated with I). The four lateral pairs of mesenteries were namely at the base united with each 

 other, two and two (on the figure designated with spaced-out lines) , while all other mesenteries, excepting 

 the directives, do not reach so far towards the centre of the pedal disc. The 10 pairs of the second order (II) 

 show the same expansion on the pedal disc as in 5. tuberculata. The muscles of the mesenteries recall those 

 of the same species, though they are weaker, this is possibly connected with an individual variation, which 

 I cannot decide as I have had only one specimen for examination. The fertile pairs of mesenteries, alternating 

 with the 34 sterile and filament-bearing pairs, were developed only in the proximal part of the body and pro- 

 vided with rather few ova; they were, as in S. tuberculata., devoid of filaments. 



Textfig. 203. Sicyonis 

 Diagram of the arrangement of the sterile 

 mesenteries. 



Sicyonis variabilis n. sp. 



PI. 3. Fig. II. 



Diagnosis: Body in contracted state more broad than high. Sphincter weak, reticular. Tentacles 

 about 70 (67 — 74) in number, with a thick mesogloea which does not form any basal swellings at the base, 

 cylindrical to conical, in contracted state with irregular, transversal furrows. Longitudinal muscles of the 

 tentacles on the outer and the inner side, at the base, equally developed. Radial muscles of the oral disc in- 

 terrupted at the insertions of the mesenteries. Actinopharynx ordinarily long. Pairs of mesenteries variable, 

 unto about 100 or a little more. A variable number of perfect pairs (to 21) and a smaller number of pairs, 

 in which one mesentery is perfect, the other not. The arrangement of the mesenteries very variable, unequally 

 developed on both sides of the directive plane. The folds of the longitudinal muscles of the mesenteries as 



