15 128 Proceedings of the Royal Irish Academy. 



Receptacles are only known in the wider forma of the plant ; they arc 

 unisexual, and apparently normal even in the smallest examples, ripe 

 antheridia being noted in a receptacle only 2x2 mm. 



The chief reasons for regarding var. muscoides as a form of F vesiculosus, 

 are the unisexual conceptacles and the fact that it is clearly linked with var. 

 halticu8. It is true the specific identity of the latter is not quite certain ; 

 but tlic nature of its conceptacles precludes the possibility of its being a form 

 of F. spiralis. The only other species with which var. balticus or var. muscoides 

 could be connected is F. ceranoides, but as seen growing there is nothing 

 suggestive of any link with the dwarf forms of that plant. A hybrid origin is 

 possible, but scarcely probable, since var. muscoides occurs in profusion where 

 /•'. ceranoides is completely absent. The principal objection to its being a 

 variety of F. vesiculosus is its elevation on the shore (above F. spiralis and 

 Pelvetia) ; but this, as pointed out in the ecological section, can be explained 

 by the high water-content of the substratum. 



Ascophyllum nodosum var. Mackaii, comb. nor. 



From the historical standpoint this is one of the most interesting of the 

 Irish seaweeds. It was first described from the Eoundstone neighbourhood 

 by Dawson Turner in 1808 (" Hist. Fuc," PI. 52), and is the earliest algal 

 record from that well-known locality. It still occurs in profusion at Round- 

 stone, being found in September, 1911, between the bridge and Ballinahinch. 

 The plant cannot be certified from any other station in Ireland, and, with the 

 exception of a few localities in W. Scotland, it is unknown elsewhere in the 

 British Isles. Turner's remarks will, therefore, be of interest. He states : — 



" For the present very interesting addition to the Catalogue of British Fuci 

 we are indebted to Mr. James Townsend Mackay, to whom I am also obliged for 

 the specimen here figured, and by whose name I have ventured to call it, as I find 

 no description of it in any preceding author, in memory of the services that he has 

 rendered to the botany of these islands, particularly by his discoveries in Ireland, the 

 south-west districts of which, a part hitherto least known to naturalists, he has more 

 than once, under the auspices of Dr. Scott, explored with extraordinary zeal and 

 success. It was in one of these excursions, in the summer of 1805, that he met 

 with the plant here figured, in a small creek at the upper end of Birtebui Bay, 

 near the hill of Cahil, Cunnamara, but nowhere else. He informs me that he 

 could not find a single specimen attached to the rocks, but it was all lying in loose 

 balls upon the shore, and in such quantity as to entirely cover that part of the 

 strand upon which it was thrown. With it was F. nodosus, which, though 

 produced in great abundance upon rocks in the neighbourhood, seemed to exist at 

 that place only in a similar manner, without being fixed to anything ; both of 



