IM'.I'OKT ON Till: ACTINI AIM \. 123 



Tribe VI. Ckuianthe^;. 



Actiniaria with numerous unpaired septa and a single ventral oesophageal groove; 

 the septa are longest on the ventral side and gradually diminish towards the dorsal 

 aspect; the two septa attached to the bottom of the oesophageal groove (directive septa) 

 are remarkably small, and are distinguished in this way from the other ventral septa. 



I have made no further anatomical investigations of the Cerianthese, and cannot 

 even complete the statements which were formerly made by von Heider (Sitzungber. d. 

 Wiener Akad. Math. Naturw. CL, Bd. lxxix. Abth. 1, p. 204, Jahrg., 1879), and my 

 brother and myself (Aetinien, p. 107). From these we cannot even certainly determine 

 what position the animals occupy in the circle of the Actiniaria, and whether or not they 

 ought to be placed in one of the known principal divisions. They are distinguished from 

 all the forms previously discussed, except the Edwardsise, by the fact that they want the 

 paired arrangement of the septa — at least up to the present it has not been observed in 

 them. They come nearest the Zoantheae, as they have only one oesophageal groove ; the 

 septa also appear not to be disposed in a circle, but in the region of a limited zone of 

 growth, which, however, lies dorsally, not ventrally as in the Zoanthese. In this case the 

 largest septa are found in the region of the oesophageal groove, and the septa gradually 

 decrease in size from that point to the opposite end of the sagittal axis; two pairs of very 

 small septa lie under the oesophageal groove, to which the name of directive septa is given 

 more from their position than from their anatomical constitution. 



Family Cerianthid.e. 



Ceriantheae with a double corona of tentacles, marginal principal tentacles and circum- 

 oral accessory tentacles, posterior end of the body rounded, without sphincter. 



Cerhirrfhus, Delle Chiaje. 



Cerianthidse with aboral pore, with a sheath consisting of mud, sand granules, and 

 nematocysts, in which the posterior end of the animal lies as if in a case. 



Cerianthus americamis. 



Cerianfh it* ttnirririiiiii.-t, Vcrrill, Memoirs Boston Soc, vol. i. p. 32, I860. 



Habitat— Station 321. February 25, 1876. Lat, 35° 2' S., long. 55° 15' \Y. 

 Depth, 13 fathoms. One specimen. 



Dimensions. — Length of the animal (in the contracted condition), 12 cm.; breadth of 

 the oral disk, 3"5 cm.; length of the inner tentacles, 2-2"5 cm. ; of the outer tentacles, 

 4-5 cm. 



