126 



ACTINIARIA 



pharynx as part of the oral disc. The actinopharynx is short and longitudinally sulcated. The two narrow 

 siphonoglyphes are only little differentiated, symmetrically placed and devoid of aboral prolongations. 



Anatomical description: For the anatomical examination I have used the type-specimen of 

 Phellia crassa and a piece of the distal part of Cactosoma abyssorum (Danielssen has sectioned the lower 

 part), I have, besides, more closely examined certain parts of the specimens from the other stations. The 

 ectoderm of the physa is rather high and contains nematocysts of the same size as those of the scapus. The 

 ectoderm of the scapus is a little lower and provided with a cuticle and conspicuous "#a/cam^>a-papillae". 

 It contains typical nematocysts 10 16 X 2 2,5 p in size. The ectoderm of the capitulum is devoid of a 

 cuticle and is higher than the ectoderm of the scapus. Its nematocysts are very numerous and much larger 



Fig. 150 



Fig. 151 



Fig. 152 



Fig. 149 



Textfigs. 149 152. Cactosoma abyssorum. Transverse section through the sphincter (fig. 149), 

 through a pennon (fig. 150) through a parietal muscle (fig. 151) and through an imperfect mesen- 

 tery (fig. 152). The sections of the mesenteries are taken from about the middle of the column. 

 Im: longitudinal muscles, ec: ectoderm, en: endoderm. 



(20 26 X 2,5 n) than those of the scapus. They are sometimes a little curved and tapering in the distal 

 end. Between the nematocysts there are scattered spirocysts of the same size as those of the tentacles, they 

 are, however, much sparser than in the capitulum-ectoderm of Halcampa. The mesogloea of the scapus is much 

 thicker than that of the capitulum and of the physa, but also in these latter regions the mesogloea may be 

 thickened, according to the state of contraction of these parts. The sphincter is mesogloeal, but weak and 

 of about the same appearance as the sphincter of Halcampa. In position it likewise agrees with the sphincter 

 of this genus. Also here the sphincter is drawn into the basal region of the tentacles, and the ectodermal 

 muscles of the tentacles and of the oral disc expand over the upper part of the sphincter (compare Halcampa!). 

 I have in another work (1902, p. 45) given two figures of the sphincter of a specimen of Phellia crassa from 

 the Olga-Expedition, here I reproduce a transverse section (textfig. 149) of the sphincter of the type-spec- 

 imen of Cactosoma abyssorum. These figures seemingly correspond well with each another. The strong thick- 

 ening of the mesogloea on figure 8 (1902) is due to a strong contraction of the capitulum, and is of no im- 



