PROCEEDINGS OF SOCIETIES. 65 



rare little alga — Dictyosphcerium reniforme (Bulnlieim) — in a 

 gathering lately made near Snowdon in North Wales, thus new 

 to Britain. This he identified from the description and figure 

 given in Eabenhorst's " Kryptogamen- Flora von Sachseu, &c. ;" 

 the figure, however, he thought, must have been drawn from a 

 specimen, or rather group or family, somewhat distorted by the 

 pressure of the covering-glass. The individual cells stand more 

 regularly than is there depicted ; they are naturally posed with 

 their concave side, that is the sinus of the reniform cell, towards 

 the centre of the group, and it is by the sinus that they are 

 attached (by whatever means that may be) to the slender stipes. 

 This stipes on each self-division of the cells at the summit (seem- 

 ingly usually into four), becomes itself branched. The colour of 

 the cells is a deep green, being densely filled with contents ; 

 reminding one considerably in this respect of those of Nephrocy- 

 tium, in which plants the cells, likewise, are reniform, but not so 

 distinctly so as in Dictyosphcerium reniforme. So densely filled 

 were the cells, that the two eye-like granules inferred in the figure 

 given in Eabenhorst, did not at all present themselves in the 

 Welsh specimens. 



Mr. Arclier showed Welsh and Irish specimens of a Coelastrum, 

 side by side, to show the absolute identity deducible from the 

 marked character presented by the form. This form he would 

 refer to Coelastrum microporum (Al. Braun), as given in a note 

 (but without a figure, and only briefly referred to, hardly 

 described) in Braun's work (" Algarum unicellularium genera 

 nova et minus cognita," page 70.). The group (coenobium) is 

 formed of rather large cells, externally globularly rounded, their 

 margins, where in mutual contact, being straight, and leaving at 

 the angles exceedingly minute, somewhat triangular interspaces, 

 like very minute pores, leading into the central cavity, charac- 

 teristic of the forms appertaining to this genus. Mr. Archer was 

 able to present some specimens showing some of the cells with a 

 young coenobium within, formed from the contents of the parent 

 cell; and these were seen to be quite like the parent in all respects as 

 regards form of the cells and their mutual arrangement, diff'ering 

 only in size. Simultaneously therewith Mr. Archer was able to 

 show another form of Coelastrum, obtained on his late brief visit to 

 Wales, which was not referable to either of the remaining forms 

 as described by Nageli, though perhaps showing most affinity with 

 Codastrum cuhicmn (Nag.), but differing in each cell possessing 

 but one process or tubercle-like appendage, not three. These 

 likewise showed various conditions of growth of the young 

 coenobia within the mother-cells, from the earliest stage, the most 

 minute of which showed the full character of the cells, each with 

 the truncate tubercle-like process. It seems to differ quite 

 from C. sphericum (Nag.) by the cells possessing this process and 

 not being, like those of the species just referred to, conically 

 rounded. For this form, Mr. Archer would propose the name 

 Coelastrum camhricum. 



VOL. VIII. NEW SER. E 



