184 



Proceedings of the Royal Irish Academy. 



mesenteiies, 12 pair.s perfect ; the [rish t'oini has 34 pairs, 21 pairs perfect, 

 at least. 



1 



Disc Tkstaclbs. ' Mauoinal Tentacles. 



1 



Name of Specimen. . f. 



2nd 3rd 

 cycle, cycle. 



ToUil. 



1st 

 cycle. 



2nd 

 cycle. 



1 3rd 

 cycle. 



4th 

 cycle. 



Tdtal. 



lArge Iiish, ... 5 



15 



• 

 11 



1 ' 

 1 



12 

 



31 



6 



15 



21 



26 



GS 



SniMI Irisli, 



r. 



14 



21 



5 



14 



20 



20 



GO 



Ucrlwig'a obltcliu, . 



G 



G 



24 



1 



6 



G 

 G 



12 



12 



24 



48 



i 



(Ydiing.) 



G 



C 



12 



G 



1 



24 



48 



llHrlwig'g lijirffiJ 2, 

 (l^irgcr lli.'in I.) 



G 



1 



G 



8 



20 



«! • 



12 







24 



48 

 42 



IIorKiK'n iiyirf«» 3, 



1 



6 6 



10 

 



22 

 13 



Irn-Riilar. 



lliTl»is'»pr«/Mi»rf«< 1, 



G 



7 



6 7 



13 



»! 



52 



Hertwig'n pn/uMJiu 2. 









12 



1 



6 ! 



1 



G 



12 



" i 



48 



III tlie li^ht iif thes» facts, it loolts as if in this f];e.iins the iiidiviiliial 

 werea law unto iUHelf,nii<l as if the ililFereiice.s in tentacle numbers and body- 

 wall furrows were imlividual, nutritional, or other variations. It is 

 coneeivable that " C. jnofnndm" is constituted by sporiincns which grow up 

 quickly and attain large size Ijefore forming more than 12 di.sc-tentaclcs, and, 

 perliaps, ihen cease growth, as far as tentacle-formation goes. The Irish 

 8l>ecinieus seem to be a case of difference in rapidity of growth in size, but 

 not in tentacle formation. The unusual body-wall ridges of " oWrr^jts " may 

 similarly lie a sjiecial individual overgrowth of me.sogloea, which at some 

 point of development started its fastest increase in bulk at points inter- 

 mediate betwi^n the usual and original growth-centres. One is bound to 



' Hertwii; had 5 s|>eciniens of rigidnt, of which I have included :< in the t^tblc, and 

 hare uunibcred 1, 2, 3. He described another a.s rujuliis in 1882, and changed it to 

 obltct^u in 1888. His 2 riijulm 8[>ccimens not in the talde »ecm to be regular ; same 

 arrangement of tentacles aa ol>lerltis. A certain number of the figures in the table are 

 not .•vctually stated by Hertwig, but can be deduced from his account. 



