194 PROCEEDINGS OF SOCIETIES. 



Kichardson concluded by observing that he had some other 

 sections of the organ in a weak osmic-acid solution, and if it 

 led to any further disclosures concerning the structTire of the 

 cells, he would exhibit them at a future meeting of the Club. 



Extremely minute Cosmarium-form with zygospore, held to be a 

 new species, exhibited. — Mr. Archer showed conjugated examples 

 of an extremely minute Cosmarium, so minute, indeed, that it 

 would seem to merit the name, and most likely keep it.of C. oninu- 

 tissimum. The zygospore is ellipsoidal or oblong, dark tinted, of 

 purplish or bronze-like hue, thick walled, but contents green. The 

 Cosmarium itself resembles several, perhaps most so C. pusillum, 

 Breb. ; but minute and readily overlooked as it may be in itself, 

 it is doubtless quite a distinct thing. But more on a future 

 occasion. — Mr. Archer likewise showed the conjugated state of 

 Didymoprium Borreri, rarely found in that state, common as is 

 the species ; E.alfs' figure is very graphic. 



Exhibition of Oocystis setigera, Arch. — Mr. Archer likewise 

 exhibited examples of Oocystis setigera, ejus ; he had never found 

 this seemingly well-marked form except in a restricted locality in 

 Connemara, and these were from the same site. 



Microgrom.ia mucicola, Arch., n. s., exhibited. — Mr. Archer also 

 exhibited the rhizopod he had named Microgromia mucicola 

 (seemingly a distinct form from Microg. socialis), this time 

 nestling in the mucus of Cosinocladium Saxonicum, de By. ; he 

 had never found it before except imbedded in the mucus of the 

 equally rare alga of similar habit — his quondam Dictyosphceriiim 

 constrictum. 



2lst December, 1876. 



New Species of Chlorochytrium (Cohn), exhibited. — Professor 

 E. Perceval Wright showed examples of a new chlorophylla- 

 ceous parasitic alga inhabiting the living tubular envelopes of 

 several species of Schizonema — and doubtless forming a new 

 species of Cohn's interesting and lately founded genus — Chloro- 

 chytrium — tlie type species inhabiting Lemna trisulca, and 

 named by its discoverer Chlorochytrium lemnce. Like that 

 species, the present reproduces by zoospores, which impinge 

 (often in great numbers) on the diatom filaments, gradually 

 penetrating them, and growing therein into new plants. The fully 

 formed plant is subglobular, or depressed in figure, the endo- 

 chrome disposed in parietal masses, and often showing strings 

 of plasma, nearly colourless, radiating from the nucleus. Dr. 

 Wright is working out the history of this highly interesting form, 

 and he hoped ere long to be in a position to describe it at length 

 with illustrations. 



Helicomyces roseus, exhibited — Mr. Greenwood Pim showed ex- 

 amples of Helicomyces roseus, a rare mould, which he had found 

 on the cut stump of a tree in Tassaroe demesne, Co. Wicklow. 

 It does not appear to have been published anywhere as British, 

 not appearing in either Cooke's ' Manual' or in ' Grevillea,' as 



