ARCHER DN STEPHAN03PH2ERA PLUVIALIS (COHN). 151 



After which was then read the following paper : — 



Record of the Occurrence, new to Ireland, with Note of a pecu- 

 liar Condition of the Volvocinaceous Aloa Stephanosphjera 

 pluvialis (cohn), and observations thereon. by wllliam 

 Archer. 



The discovery in Ireland of the very interesting and very beautiful, and 

 apparently very rare organism, Stephanosphcara pluvialis (Cohn), would 

 in itself alone be worthy of a record in the " Proceedings" of this So- 

 ciety. But inasmuch as, whilst I had a supply of this " Yolvocine" in my 

 possession, a remarkable phase or condition in its history, so far as I am 

 aware not before observed in this form, though not without parallels 

 elsewhere, presented itself to my notice, the value of that record be- 

 comes thereby in so far enhanced. 



Spending an evening in the month of June last at Bray, I took a 

 walk upon the " Head," promising myself indeed not much of interest 

 (save the beautiful view) from its dry and rocky summit. The weather 

 had lately been showeiy, and during the day a considerable quantity of 

 rain had fallen. This had left behind small deposits of rain water in a 

 few little hollows amongst the rocks. In oDe of these tiny pools, I per- 

 ceived the water tinged with a beautiful light green colour. A few mo- 

 ments' inspection, even without a lens, was sufficient to indicate that 

 this green hue was due to the presence of myriads of some " volvocina- 

 ceous" plant ; and, with a lens, I soon perceived, by the annular and 

 band-like green portions of the organisms, as they appeared under so low 

 an amplification, alternately brought to view, that I had had the good 

 fortune to encounter that seemingly rare organism Stephanosphcera plu- 

 vialis (Cohn), which Professor Cohn journeyed from Breslau to Hirsch- 

 berg to see, and for the occurrence of which I can find hitherto but six 

 localities, the present making a seventh. These are — Saltzburg, found 

 by Werneck, Zambra, and von Prantzius ; Hirschberg, in Silesia, by 

 von Plotow and Cohn ; summit of Heuscheur in Grafschaft Glatz, Si- 

 lesia, by Cohn ; Lapland, by Wichura ; Schneeberg, Saxony, by Raben- 

 horst ; Scotland, by Strethill Wright ; and now lastly, at Bray Head, 

 Ireland, by myself. It is very probably more common than these few 

 localities might indicate, but these are at least all the records I can 

 find. 



As may be imagined, with no small amount of avidity I pocketed a 

 supply of the treasure thus placed at my feet. The specimens so ob- 

 tained afforded an opportunity in a great measure to follow out the 

 statements made in Cohn's beautiful memoir,* with respect to the orga- 



* Cohn, " Ueber eine neue Gattung aus der Familie der Volvocinen," in Siebold und 

 Kolliker's "Zeitschrift fur wissenschaftliche Zoologie," Band IV. (1852), p. 77, Tab. VI. ; 

 also "Annals of Nat. Hist," 2nd Ser., vol. x., pp. 321 et seqq., 401 et seqq., PI. VI. 



Y 



