36 DUBLIN NATUEA.L H18T0ET SOCIETY. 



have supposed them to be stray waifs, brought from more temperate regions by 

 tides or currents. I cannot subscribe to such ideas, from the fact of Mr. Sawers hav- 

 ing found fronds of his Desmarestia in tolerable abundance during a large portion 

 of last year (1853), even up to near Christmas, and as Desmarestia undergoes 

 decomposition so very rapidly when dead, I cannot believe it possible those 

 fronds which we see here in excellent preservation could have been knocking 

 about on the ocean for months. I therefore conclude they grew not far from 

 the spot where Mr. Sawers found them. 



In conclusion, I would wish to remark on the doubt implied on Dr. Mon- 

 tague's paper as to the alga in question being a Desmarestia. The structure 

 certainly agrees with that of ligulata. As my specimens were quite dry when 

 they reached me, I could not determine if the single-jointed tube mentioned by 

 Dr. Harvey as traversing the fronds exists in Pinnatinervia. Should it be found 

 there, I have no doubt that it will appear in the nervures and midrib. Altogether 

 the question is one of much interest to the algologists, and I look forward with 

 expectation that Dr. Harvey will investigate the subject on his return, and 

 clear up existing doubts. 1 think it very evident that if the Pinnatinervia be 

 a Desmarestia, and if the tubercles I have observed on ligulata be the true Iruit, 

 then Dr. Harvey will have to construct the genus anew, for the diagnosis does 

 not meet the existing facts. 



MAY 18, 1855. 



ON THE ADVANTAGE TO BOTANY OF LOCAL LISTS, AND NOTES WITH REFERENCE 

 TO THE ALG^ OF THE EAST COAST OF IRELAND. BY GILBERT SANDERS, M.R.I.A. 



As I have not seen a list of marine algae which have been collected from time 

 to time by various algologists in our bay and the neighbouring shores, I am in- 

 duced to offer a contribution to the formation of a local list ; and 1 pi'opose that 

 we consider Balbriggan as the northern limit, and Wicklow Head the southern 

 boundary, of what 1 would beg leave to term the Dublin district of coast. I have 

 selected these two extreme points, on account of their being favourable places 

 for collecting, and being so easily accessible by rail, as are also all the interme- 

 diate spots along the line of coast. The eastern shores of Ireland, bordering on 

 the Irish Sea and St. George's Channel, have not been sufficiently explored. 

 There is an impression that these shores are not prolific of species. One of our 

 most eminent algologists said to me, about four years since, that the Dublin 

 shores were not favourable for the study of algology; but I think that opinion 

 was incorrect. My friend. Dr. Cocks, of Devonport, spent about two hours at 

 Bray, and a similar time at Howth, in the summer of 1853, and in these two 

 hasty visits he saw upwards of tifty species. Low water, at spring tides, is the 

 most favourable for procuring the rarer species and most perfect specimens. 

 The rock-pools, which are only uncovered at spring-tides, are the best spots for 

 searching, these being the favourite habitats of many scarce algae. To search 

 these pools satisfactorily, we require considerable light, for without it we can- 

 not see to any depth, or even the sides of the submerged rocks under the shelter 

 of which the more delicate filamentous algae grow. On the south-western shores 

 of England, and the southern, western, and northern shores of Ireland, and all 

 the shores of Scotland, the time of low water spring-tides is from three hours 

 before noon to three hours after, during which there is sufficient light for col- 

 lecting; but, unfortunately for algology, in our own immediate district, the 

 same state of tide occurs at six or seven o'clock, morning and evening ; there- 

 fore, the examination of pools, at low-water springs, can be conducted on our 

 coast only for about three or four months — viz., the summer — and we are ex- 

 cluded from them altogether during the autumn, winter, and spring, — seasons 

 fully as interesting to the algologist as the summer months. The beautiful pen- 

 cilled tufts of the Sporochnac8B are only visible in spring, and many algae are not 

 in perfection except in winter. Possibly it may be owing to the unsuitableness 



