130 Proceedings of the Royal Irish Academy. 



continuous with the thin lining in the peduncle. But in cases where 

 they are not so closely packed, the homy crust can be seen in process 

 of growth, at first as a delicate creeping stolon, and afterwards 

 expanding on all sides as the budding proceeds. Probably, therefore, 

 the descriptions hitherto given of T. Tiorenii and T. pedicellata, as 

 " scattered, rising from a delicate creeping stolon," can only have 

 been founded on young colonies where the crust had not commenced 

 to form. It would appear to be a character of generic importance. 



I would therefore propose to emend Mr. Hincks's diagnosis of the 

 stem by adding the character, formerly given by Sars — but with limita- 

 tions : "stem forming a continuous crust, or a creeping stolon in 

 small colonies, from apertures in which the peduncles arise." The 

 presence of such a chitinous or horny crust, in many ways resembling 

 that of Hydractinia, in this Ctenostomatous group, is rather peculiar, 

 and I hope to be able to study its formation further. 



1 . Triticella flava, Daly ell. 



TriticeTla flava, Daly., Eem. An. ii. 66, pi. xix. fig. 1 ; Sars, 

 Christiania Vidensk. Selsk. Forh., 1873, 398 ; ISTorman, Ann. ]^. H., 

 Peb. 1879, p, 138 ; Hincks, Brit. Mar. Polyz., p. 543. 



This species was founded by Sir J. Dalyell on a form he obtained 

 from Scotland, but his description is not sufficiently minute, nor his 

 figure sufficiently trustworthy in details, to make sure what form 

 he actually had under observation. Canon Norman is of opinion that 

 it is identical with T. horenii, Sars, which species he has obtained 

 also from Scotland. His specimen was obtained near Oban, growing 

 on Saccidina carcini, this parasitic Cirripede being also the habitat of 

 Dalyell's form. T. horenii has, however, been obtained from several 

 Irish localities, but in no case growing on SaCcuKna, so that the fact of 

 habitat, to which Norman attaches some importance, is evidently of no 

 account. The peduncle in T. flava is very short, being only about 

 half the length of the cell. In most of the Eoyal Irish Academy's 

 specimens of T. horenii, the peduncle varies considerably in length, 

 being generally two or three times the length of the cell ; but in one 

 group there are several specimens in which the peduncle is not 

 even half the length of the cell. Again, in T. pediceUata, the ordinary 

 length of the peduncle is two or three times that of the zooecium, 

 but I have also specimens of this in which the peduncle is only about 

 half the cell-length. It is pretty evident, therefore, that the length 

 of the peduncle is of little moment. As compared with Dalyell's- 



