REPORT ON THE ACTINIARIA. 57 



into muscular septa and reproductive septa. The animals do not appear to draw the 

 oral disk over the mouth, though a mesodermal muscle is present. 



The external appearance of the Actiniae, for which I have formed the new genus 

 Ophiodiscus, recalls that of Anthea cereus, as the tentacles are of great length, project in a 

 single row on the outer margin of the oral disk, where it is turned over into the wall, and 

 hang down like flowing hair over the side walls of the body. The margin of the wall was 

 also not drawn over the oral disk as in the Paractidse. It would, however, be rash to 

 conclude from the form presented by the animals before me that they are quite incapable 

 of concealing the oral disk, and the more so as I succeeded in finding a mesodermal 

 sphincter. It is possible, however, that, considering the size of the body, the sphincter is 

 not very strongly developed, so that the contraction caused by it is a slow process. 



A further point which distinguishes Ophiodiscus from the other Paractidse is the 

 constitution of the tentacles. As one wall of the tentacles is formed by the prolongation 

 of the body wall, the other by the prolongation of the oral disk, they show the same 

 differences in the distribution of the muscles which characterise the said sections of the 

 body wall. The former only has longitudinal muscles, the latter is without muscles and 

 is correspondingly thinner walled. 



The differentiation of the septa into sterile septa with muscles and reproductive septa 

 with weak muscles is still more important. The latter are extremely rudimentary, and 

 have even lost the mesenteric filaments ; whilst in other Actinias a distinct graduation in 

 size prevails in the separate cycles of septa, there is a pronounced distinction between the 

 smallest muscular septa and the reproductive septa. It may be advisable at some future 

 time to erect this form into a special family. 



Ophiodiscus annulatus, n. sp. (PL X. figs. 1-10). 



Wall surrounded close below the tentacles by numerous circular furrows, caused by 

 the sphincter, which become less distinct towards the lower part of the wall. 



Habitat. — Station 299. December 14, 1S75. Lat. 33° 31' S., long. 74° 43' W. 

 Depth, 2160 fathoms. Four specimens. 



Dimensions. — Height, - 5-l"8 cm. ; breadth of the oral disk, 2"0-4'5 cm.; breadth of 

 the pedal disk, TO-3'5 cm. 



Before proceeding to describe Ophiodiscus annulatus, I wish to make a few preliminary 

 remarks as to the state of preservation in which I found the animals in question. It was 

 unfortunately extremely unsatisfactory, which I regret the more as they are a particularly 

 interesting form. In all the specimens the tentacles were tattered and frayed out at 

 the end, and there were rents here and there in the wall between the insertions of the 

 septa. The largest specimen was so much destroyed that I could not take any measurements 

 from it. All this must be ascribed to the fact that the animals came from a great depth, 

 and had been injured in hauling up the dredging apparatus. The animals have, moreover, 



(ZOOL. CHALL. EXP. — PART XV. 1882.) P 8 



