REPORT ON THE ACTINIARIA. 33 



II. Paractini^, 



Family 10, Sicyonid^. 



Genus Sicyonis, R. Hertwig. 



Sicyonis elongata* n. sp. 



The animal is elongated, with about 54 tentacular papillse ; the genital mesenteries 

 project into the coelenteron from between the oral disc and the body -wall. 



Habitat. — Station 244, June 28, 1875 ; 2900 fathoms. One specimen. 



Dimensions. — Height, 7 cm. ; breadth about 3 "5 cm. ; diameter of the pedal 

 disc, 2 cm. 



The sole specimen at my disposal was so strongly contracted that one could hardly 

 find the entrance to the oral disc. The pedal disc was also exceedingly small, due 

 partially, no doubt, to contraction. Had the specimen, which in other respects also 

 was but poorly preserved, not been so compressed in the packing, it would have had 

 the shape of a long sack sewn up at both ends. 



The external appearance of the animal is therefore essentially different from that of 

 Sicyonis crassa, the body of which is flattened like a cake ; but in the internal structure 

 there is considerable agreement between the two. The sphincter, the muscles of the 

 tentacles and oral disc, the cuticular consistence of the mesogloea, the differentiation of 

 muscular and genital mesenteries, the enormous folding of the siphonoglyphes, the 

 radial striation of the oral disc, the shape and arrangement of the tentacles, are in both 

 cases identical. I was therefore inclined to regard it as a new specimen of Sicyonis 

 crassa, had I not lighted on one distinguishing characteristic of great importance. 



The genital mesenteries in Sicyonis crassa are thin lamellae, which bear only the 

 generative organs, and spring in the angle between pedal disc and body-wall ; but in 

 this new specimen the muscles are ob\'ious, and are arranged in "muscle-pennons;" 

 the most noteworthy point, however, is, that the genital mesenteries belong to the 

 upper section of the body, lying in the angle between oral disc and body-wall ; on the 

 former they reach as far as the oral opening, and on the latter, in the form of slight 

 folds, up to the pedal disc. Mesenterial filaments do not occur on them. Since the 

 specimens of both Sicyonis crassa and Sicyonis elongata were males, the different 

 position of the mesenteries cannot be due to the difference of sex. 



Part of the animal was anatomically investigated with reference to the arrange- 

 ment of the mesenteries, and part of the body-wall, with the mesenteries in the 

 neighbourhood of the stomatodajum, was utilised for transverse sections. I was able 

 to prove the normal arrangement of the mesenteries in pairs at some points ; but at 

 certain spots irregularities occur, owing to the alternation of isolated genital mesenteries 



(ZOOI.. CHALI. EXP.— PART L.XXUl. — 1888.) Dddd 5 



