126 



PROCEEDINGS OF SOCIETIES. 



sportive character of the algae has led to much dispute some botanists insisting 

 that certain species of other authors are merely varieties. Doubts of this 

 description will be more surely cleared up by the observations of many observers ; 

 and it must also be borne in mind by botanists who are not very familiar with 

 algae, that many of them put on such variable appearances, according to the season, 

 as to lead to the belief that a summer specimen and a winter specimen of the same 

 plant must be perfectly distinct species. Whilst speaking of the abundance or 

 scarcity of some plants at the usual season of their appearance, I will read an 

 extract from a letter I recently received from Dr. Cocks, which I regard as most 

 interesting, and I look upon it as a very remarkable fact in algology. He says 

 " I have now had eleven years' experience in collecting, and have gained a certain 

 amount of practical information, which, I confess, I had heretofore not sufficiently 

 attended to. Observation and experience have taught me that there is not the 

 same regularity in the time of appearance of the marine alga3 as there is in plants 

 growing on terra firma, and that the terms annual, biennial, and perennial, are not 

 applicable to the former ; and that their growth and time of appearance are 

 governed by laws, or influenced by causes which the algologist, even of the present 

 day, is unable to explain. It is quite true that, in certain localities where I had been 

 in the habit of gathering certain species for two, three, and more years successively, 

 when I have afterwards wanted to obtain more they had disappeared, and, in some 

 instances, have never since been found. In other instances, some plants, which 

 were previously considered to be extremely rare and scarce, only picked up at 

 intervals, far and few between, have suddenly appeared in the greatest profusion. 

 Dr. Budd told me that two years ago, having found out where it grew, he could 

 have dredged thousands of specimens of Stenogramme interrupta. Last year I 

 could myself have dredged a like quantity of Sporochnus pedunculatus and 

 Haliseris polypodioides, neither of which species I ever took before to say plentifully. 

 A few years ago the mud bank at Cremil Passage was strewed over at low water 

 with quantities of Spha3rococcus coronopifolius, since when I have only taken two 

 specimens. You will, of course, remember when we gathered such a quantity of 

 Dasya arbuscula atFirestone Bay. I have carefully hunted over the same ground every 

 year since, and have never seen a single plant ; even the very commonest plants 

 sometimes disappear for two, three, or more years such as Delesseria hypoglossum, 

 D. ruscifolia, Nitophyllum punctatum, &c." Such is the experience of Dr. Cocks. 

 It would be very desirable for other algologists to note the appearance and disap- 

 pearance of plants from a locality, and then to endeavour to trace out the cause. 

 With the view of promoting the object of this paper viz., the preparation of a list 

 of all recorded algae found on the shores between Balbriggan and Wicklow Head 

 I suggest that other collectors will look over their collections and give our secretary 

 lists of their gatherings on those shores, that we may have as large a catalogue as 

 possible of the marine botany of the district. I hope soon to increase the list, 

 which, for the present, is confined entirely to Mrs. Dave's collection ; and before 

 concluding I would beg to draw the attention of the members to the very beautiful 

 and natural appearance of the specimens which were prepared after the method 

 laid down in the " Seaweed Collector's Guide," by Dr. Cocks, of Devonport. 



LIST OF MARINE ALG& COLLECTED AT SKERRIES, NEAR THE NORTHERN LIMIT OF 

 THE PROPOSED DUBLIN DISTRICT, IN THE SUMMER OF 1854. 



MEIANASPERME.E. 



Order. 

 Fucaceae. 

 Sporochnaceae. 



Laminariaceae. 



Dictyotaceas. 



Cystoseira ericoides. 

 Desmarestia ligulata. 



aculeata. 



viridis. 



Laminaria digitata. 



saccharina. 

 Chorda filum. 

 Taonia atomaria. 

 Dictyota dichotoma. 

 Stilophora Lyngbyaei. 



Order. 

 Dictyotaceas 



Chordariaceae. 



Ectocarpaceae. 



Dictyosiphon foenicu- 



laceus. 

 Chordaria flagellifor- 



mis. 



Mesogloia virescens. 

 Leathesia tuberifor- 



mis. 

 Elachista fucicola. 



,, scutulata. 

 Cladostephus verticil- 



latus. 



