298 Proceedings of the Royal Irish Academy. 
by Professor Eeinsch,* for two new and singular exceedingly minute 
Chroococcaceous forms, that examples of specially figured cells were 
known in this family of Algae. Here we have unicellular Chroococca- 
ceous plants existing quite free and unattached, and, therefore, in no way 
acted upon by mutual pressure, or capable of being modified in outline 
by any mechanical exigency of position of growth, and at same time 
offering very characteristic and even complex figures. Inasmuch, 
therefore, as I apprehend Professor Reinseh's work must be but little 
known in this country, and as the specialities of his forms seem not yet 
clear, upon which, possibly, observers with us, should they encounter 
them, might be able to assist in throwing light — and, further, inasmuch 
as I am myself acquainted with two other figured, but less complex, 
also very minute forms, clearly of similar nature, though not absolutely 
fitting into the genus, as characterised by Reinsch — for these reasons it 
has appeared to me that a notice thereof might find a fitting place in 
these pages, accompanied by a reproduction of Reinsch's, as well .as by 
a sketch of my own forms (PL XXL), and (although no further light can 
be shed upon them than that there they are") become, at same time, 
a not wholly unwelcome contribution to English readers. 
Perhaps, before endeavouring to convey an idea of my two less 
striking but new forms, it would be best to reproduce Reinsch's Latin 
description of his genus, and of his two forms falling thereunder, ex- 
amples of one of which I have also once myself met with in a gathering 
made in County Westmeath. It is as follows : — 
Class, Phycochroynacem. 
Pamily, Chroococcacece. 
Genus, Tetrapedia (Reinsch). 
Cellulae solitariae aut rarius consociatione individuorura plurium fa- 
milias ex cellulis binis, quaternis aut 16is exstitutas constituentes, in 
sciagraphia quadraticse, cellula singula incisuris quaternis in cellulas 
filias quaternas dilapsa, cellule filise post divisionem individuas singu- 
las se prsebentes, incisurarum directio in marginum lateralium direc- 
tione perpendiculari aut in angulo semirectangulo versa ; cellularum 
xnteranea granulosa, colore serugineo. 
Tetrapedia gothica. P. Reinsch. 
Cellulse in sciagraphia quadraticse, margines laterales in medio non 
profunde incisi, lobuli in medio paulo emarginati; cellulse evolutiores 
quadripartitae, incisurarum directio in marginum lateralium directione 
perpendicularis. (PI. XXL, figs. 1 to 7). 
* Die Algenflora des mittleren Theiles von Franken," by Professor Paul 
ReinsGh, Niirnberg, 1867, p. 37, t. ii., fig. i.,' andt. i., fig. vi. Also in the author's 
Memoir " De speciebus generibusque nonnullis novis ex Algarum et Fungorum 
Qlasse" ri867, p. 30, t. i, fig. Ai.; ex vol. vi. " Act. Societ. Senckenb."). 
