150 Proceedings of the Royal Irish Academy. 



"Where ihe scapus ends and the eapitulum begins there is an uppermost ring 

 of twelve tubercles to be recognized : these, for convenience, may be termed 

 " coronal " tubercles, but that does not imply that they are different from the 

 others — simply that they mark the upper limit of the scapus. The tentacles 

 are arranged curiously, in five cycles, as a rule regularly developed — 

 6 + 6 + 12 + 24 -}- 48 = 96. The largest are of course the innermost, succeeding 

 ling smaller, the outermost very smalL The tentacles of the 

 three inner cycles are provided with large and deBnite swellings of mesogloea 

 on the aboral si'ie at the bus..'. Those of the fourth cycle have rather smaller 

 in outwards like bridges i" the extreme margin of the 

 oral disc, and run over th< _ it and down the outside of the eapitulum. 



'.hen, since there are twenty-four tentacles in the 

 fourth cycle, and - . lently twenty-four ridges I the margin of the 



eapitulum, as the ridges run downwards they converge in pairs, the two 

 individu _ another just '.each one of the 



nal tubercles, into which I _ _ -. This may be differently 



HaddoD put it, - that there are twelve capitular ridges 



which bifun the tentacles of the fourth cycle ; 



but, foi '■ hich will appear, I prefer the former way of stating the case. 



the lift: .1 and have no basal swelli: _ 



thoi g !y. their bases are slightly thickened. Reference to PL XVI, 



11 help to make this clear. 

 U. ! d scribed in the general terms above 



-bow how they vary among them- 

 . .w many of them, although of unite typical 

 • account in minor w.; 



^ometini' 

 but all - are to in- found, and in some 



cas- . :on is much reduced and is small in 



.I,. Th< PI. XVI fig nd 40, show longitudinal 



; which the size of the b 



Other cases are 

 :id in which tl - - >1 cavity small. The mouth of 



.y. and in many degrees. It may 1«> very 

 wi tii.-i extreme, it may be 



When tin- cup is 



Dioolh outside and in, 



. margin. Often it is full of mud, 



. ;t ; the lalU-i was 



• in all the cases which 1 especially 



examined with regard to it It is thin and 



