ACTINIARIA 



193 



Fig. 183 



and, as Danielssen states, of an almost triangular form. 

 In their uppermost part they are provided with distinct 

 gonidial tubercles. 



Anatomical description. The pedal disc has a 

 rather thick cuticle. The ectoderm of the column is somewhat 

 low and contains rather numerous nematocysts 22 — 24 X 

 about 4 // in size, and numerous mucus-cells. The meso- 

 gloea is in the proximal part thin or of ordinary' thickness, 

 corresponding to the different state of contraction, but 

 swells out in the region of the sphincter and there forms 

 a thick layer; it contains small protoplasma-poor cells. 

 The endodermal circular muscles are weak, the mesogloeal 

 sphincter, on the other hand, is very strong and juts out, 

 during certain states of contraction, as a strong thickening 

 towards the ectoderm, about as the sphincter of Tealidiutn 

 cingulatum (Her twig 1882 PI. 6 fig. 2). In the upper 

 part and in the greater part of its length it occupies almost 

 the whole breadth of the mesogloea, proximally it decreases 

 rapidly and takes up only the inner 

 part of the mesogloea. The mus- 

 cle meshes are very small, in certain 

 parts very close, in other parts se- 

 parated by larger lamellae of the 

 mesogloea. Any distinct stratifica- 

 tion of the sphincter is, however, 

 not to be seen (textfig. 183). 



The ectoderm of the ten- 

 tacles is very high and contains very 

 numerous spirocysts of very vari- 

 able size, unto 53 X 4 — 6 /i ; on the 

 other hand, the typical nematocysts 

 are very sparse and 26 — 29 X 4 — (5)/^ 

 in size. In the swollen basal part, 

 on the outside of the outermost 

 tentacles, there is a specific stinging 

 organ developed (textfig. 184) , which 

 I have also observed in Tealidium jungerseni. This battery contains very numerous, closely packed nemato 

 cysts (fig. 184 w) of considerable size (74^ — 93x12 — 13/!/), which are, however, smaller than those of Tea 



The Ingolf-Expedition. V. 9. J 



Fig. 185 



Fig. 186 



Textfigs. 183 — 186. Anihosactis jan mayeni. 

 Fig. 183: Transverse section of sphincter. F"ig. 184: Transverse section of an outer- 

 most tentacle, at the basis showing the battery of nematocysts (h). Figs. 185 — 186: 

 Transverse section of an inner tentacle fig. 185 at the abaxiale, and fig. 186 at the 



adaxiale side. 



