Stephenson — Certain Actiniaria collected oft Ireland. 145 



reach the exterior. I sectioimed two examples of body-wall from another 

 specimen which had not been tampered with, one containing a pit, and the 

 other a channel going right through. Sections show that they are merely 

 rough, irregular cavities in the mesogloea, with strands of mesogloea about in 

 them ; they have no epithelial lining, only traces and remnants of cells, 

 which may have once formed a lining. The question is, are they cinclides ? 

 In the first place, it would be very unusual to find cinclides in an animal 

 with such a ponderous body-wall — they are essentially structures typical of 

 a delicate creature. In addition, they seem to me to be too large and too 

 irregular to be considered cinclides, apart from the fact that at best they have 

 only the remains of a lining of epithelium. It is just possible that they might 

 be artificially produced by rough surroundings and food — there were remains 

 of sea-urchin spines in some of the specimens, here and there, for instance. 

 It is also a possibility that they are vestigial cinclides. I have already recorded 

 a case of absolutely rudimentary and possibly vestigial acontia in Zeptoteichus 

 insignis, so that it is not altogether out of the question to suppose that in the 

 case of C. duplicate/, we have remains of what may have been cinclides when 

 the animal was quite young, and have degenerated. At any rate I do not 

 think they are genuine cinclides. 



Structure. — (i) Mesenteries. A typical specimen showed six pairs of perfect 

 mesenteries, and two extra unpaired perfect mesenteries, disposed as in 

 C. coccinea. The plan of arrangement is 6p. + 6p. + 12p. + 24p. + 48p. = 96p. ; 

 it is not carried out with exact regularity, but nearly so. The primary 

 mesenteries only are sterile. Acontia are home on some, at any rate, of the 

 mesenteries of all cycles. 1 cannot find any mesenterial stomata for certain. 

 I dissected altogether eight specimens, in order to find out, if possible, whether 

 the arrangement of perfect mesenteries and disposition of gonads was constant. 

 In all of these, every mesentery of the six primary pairs was sterile ; and in 

 every case there was at least one perfect mesentery over and above the six 

 primary pairs. In four cases there were two unpaired mesenteries of the 

 second cycle perfect, and these were in all four examples disposed one on each 

 side of a pair of directives, and with their retractor-face turned towards the 

 directives. Tn another case, the arrangement was the same, but in addition 

 the partner of one of these unpaired mesenteries was also perfect. In another, 

 there was only one extra unpaired perfect mesentery instead of two. In still 

 another, there were the usual two unpaired perfect ones, and also one unpaired 

 mesentery of the second cycle in one lateral exocoel was perfect. The last 

 case had simply one odd pair perfect in addition to the six primary pairs, so 

 that the arrangement may or may not be bi-laterally symmetrical, and the 

 additional perfect mesenteries may or may not be paired. 



R.I, A. PROC, VOL. XXXIV., SECT. B. [ ('] 



