15 116 Proceedings of the Royal Irish Academy. 



of the Kew specimens tends to support Agardh's conclusion that all three 

 varieties belong to one species, and shows that in a general way niucronation 

 is correlated with robust habit and very large utricles (points not noted in 

 the original diagnosis). The Irish plant does not agree exactly with any of 

 Agardh's varieties. It resembles closely var. Novae Zclundiac, but differs in 

 the usually blunter rnucro, and also in the occasional partial absence of this 

 structure. 



Notes on the niucronation of the four varieties are given below, Agardh's 

 description of the first three being amplified or slightly emended. 



var. tasmanicwm. — Utricles in youngest parts tapering to a long sharp 

 point; in older parts broad, cylindrical, sharply mucrouate. Distribution — 

 E. and S.E. Australia and Tasmania. 



var. Novae Zehndiae. — Utricles surmounted with a small, sharp mucro, in 

 both young and old parts of the fronds, but usually slightly more marked in 

 the younger. Distribution — New Zealand and E. Australia. 



var. californicum. — Utricles surmounted with a long or short mucro, which, 

 though sharp at first, is usually blunt later, and sometimes apparently 

 articulate. Mucro very variable in length, sometimes partially absent. 

 Distribution — Pacific Coast of N. America, (Japan 1) 



var. atlanticum. — Utricles in younger parts surmounted with a very short, 

 sharp or blunt mucro ; in older parts utricles sometimes non-mucronate. 

 Distribution — N. and W. of Ireland, Isle of Man, S.W, Scotland, Orkneys. 



The above four varieties form an irregular series with regard to their 

 niucronation. Var. californicum, although in some respects intermediate 

 between tasmawwum and Novae Zelwndiae, is apart from both in the bluntuess, 

 articulation, and occasional great length of the mucro. 



Identification of the Irish Plant. — It is certainly remarkable that so 

 conspicuous a species should have so loug escaped attention. Kuown from 

 Kilkee, and plentiful in the pools at Dog's Bay, Uoundstoue, it is almost 

 incredible that such acute observers as Harvey aud McCalla should not have 

 detected it. A single specimen collected in Bantry Bay by Miss Hutehins 

 (Cambridge University Herbarium), and two collected in 1839 from the 

 Ayrshire coast (Dublin National Museum), show that it is no recent 

 introduction. 



The plant attracted attention on the first day spent on Clare Island. 

 and on one or two occasions only was there the slightest difficulty in 

 distinguishing it at a glance from C. tomentosum. Its light-green colour in 

 summer, and preference for shallow sunny pools, cannot fail to strike the 

 collector, whilst its sturdy habit is also noteworthy. With the exception of 

 the last, these characters are not of course visible in the dried specimen, and 



