DUBLTX MICROSCOPICAL CLUB. 105 



arrangements lost, or rather, perhaps, more properly speaking, 

 the interspaces become clothed with chlorophyll-granules. At 

 first glance this might be mistaken, under a low power, for that 

 small form of Eremosphcera viriJis, de Bary, whicli originates 

 when the individuals of the ordinary large form produce simulta- 

 neously four in place of two daughter-cells ; but the evident 

 elliptic figure and the thickened poles, as well as the diff"erent 

 arrangement of the chlorophyll-contents, would, on closer inspec- 

 tion, at once distinguish them. Mr. Archer drew attention to 

 the seemingly curious very great expansion of the wall of the 

 mother-cell, almost looking as if in anticipation, rather than as 

 in consequence of the growth of a young " brood" of two, four, 

 eight, or sixteen daughter-cells ; so much so that it almost had 

 the aspect of a fresh growth rather than that of a mere swelling- 

 up of the old membrane. The genus Oocystis, Al. Braun, comes 

 very near Nephrocytium, Nag., the seemingly only very tangible 

 distinction (it is a very constant one, at the least) being the 

 reniform (not elliptic) cells in the latter genus ; but as forma 

 merely o£ more or less frequent occurrence, those referred to 

 both the genera are, indeed, very distinct and constant things. 

 There is a probably more distant affinity, too, to Polyedrium, 

 Nag., of which genus "Wittrock has described a large form (occur- 

 ring also in Ireland), and called it Polyedrum gigos, from its com- 

 paratively great size. For the same reason this form of Oocystis 

 might stand as Oocystis gigas^ 



The unlike Zygospores of txco minute smooth closely resemhling 

 Cosmaria, exhibited . proving their specific distinctness, the puzzling 

 resemblance of the forms themselves notwithstanding . — Mr. Archer 

 showed two closely resembling minute smooth Cosmaria, both of 

 which would be described as possessing elliptic semicells, the 

 ditlerences in the contours of the two forms being so slight that 

 no doubt many might say it was but straining to regard them as 

 distinct species. Still, on close examination, one could readily 

 see that, besides size, there were really very appreciable, if but 

 comparatively slight, distinction in their outlines. But all doubt 

 as to their distinctness would seem to be set aside by the marked 

 differences in their zygospores — the smaller had a quite smooth, 

 dark brown orbicular zygospore, the other a larger colourless 

 spore, beset with tapering subacute sj)ines. Mr. Archer merely 

 now brought forward these two forms, which he had never before 

 exhibited, as a very pretty instance of the wonderful inherent 

 specialities bound up with the individual entities amongst these 

 algse. 



Encysted state of Jleterophrys FocTcii, Arch. = ^phoirastrum 

 conglobatum, Greeff, exhibited. — Mr. Archer showed an example 

 of the encysted state of the not uncommon Heliozoan he had 

 called Heterophrys FocJcii, most probably identical with Sphceras- 

 trum conglobatum, Grreeif, the inner body being surrounded by a 

 doubly-contoured cyst, the outer region excluded and appearing 



