ACTINIARIA 



135 



17 u long. The periderm is thicker than the covering of the physa and imbued with detritus, especially on 

 the numerous papillae which seem to be .of the same nature as the " Halcampa-papiWae" , though they are 

 here supported by strong prominences of the mesogloea. The smooth ectoderm of the capitulum is high and 

 provided with rather numerous nematocysts, 17—18 x 2,5 u in size, sometimes a little curved, hut without 



Fig- 155 



Tcxtfigs. 155 — 15S. Andivakia mirabilis. 

 F'g- 155: Longitudinal section of the upper part of the 

 column and of the basis of a tentacle showing the me- 

 sogloeal sphincter (; tentacle, ca: capitulum, t; cuticle. 

 Fig. 1 50: Transverse section of a pennon in the lower 

 part of the actinopharynx. Fig. 157: Transverse section 

 of a perfect mesenterj' in the reproductive tract. Fig. 

 158 : Transverse section of a mesentery of the second order. 



spirocysts. Its mesogloea is thick, especially at the ridges. The endoderm of the column is somewhat thick, 

 in the physa thinner than the ectoderm. The endodermal circular muscles are rather well developed and 

 form short, paHsade-shaped folds. The sphincter (textfig. 155) is mesogloeal and strong, elongated, about 

 twice as long as the capitulum, not forming an offset, not stratified. The most distal part of the sphincter 

 much recalls the sphincter of Halcampa. It is namely here divided in somewhat fine meshes and is so much 

 elongated that the longitudinal muscles of the tentacles cover the uppermost part of the sphincter. It is 

 besides, as in Halcampa, rather close to the ectoderm. In the other, larger part of the sphincter, where the 



