308 Proceedings of the Royal Irish Academy. 
Figs. 9, 10. Diameter of cell about -jtV t to cj-oVt" 
In'ninning water (very scantilj^) near Erlangen : also (very scantily) 
near Mullingar, Ireland. 
Tetrapedia Reinschiana, nov. sp. 
Cells quadrangular, two opposite margins excavated by a wide trian- 
gular sinus, thus subdividing the cell into two broadly cuneate segments, 
connected by a wide isthmus, and somewhat convex on their lower 
margins; the other opposite margins of the cell, that is, the upper mar- 
gins of the segments, very slightly concave at the middle, somewhat 
raised towards the sub-acute minutely apiculate outer angles f" in side 
view oblong, constricted at the middle, ends rounded, 
rigs, 11, 12, 13. Diameter of largest cell met with (from angle 
to angle in both directions equal) from about syVo' to say one- third 
or even one-half smaller. 
In moor pools, Counties Dublin, "Wicklow, and Galway. 
In venturing to associate Professor Reinsch's name with this species, 
I may take the opportunity to express the great pleasure with which I 
have availed myself of his interesting papers and correspondence, 
though unable to concur with certain of his views ; and I would also 
use the occasion to thank him highly for the valuable and much esteemed 
favour conferred by his having been so good as to forward me copies 
of his memoirs. 
Tetrapedia setigera, nov. sp. 
Cells triangular, each lateral margin somewhat deeply excavated by 
a broad rounded sinus, dividing the cell into three lobes rounded at the 
ends, and each terminated by a very delicate straight bristle, in length 
about equal to the diameter of the cell ; in side view oblong, somewhat 
inflated at the middle at each side, ends rounded, and each seen tipped 
by the bristle. 
Pigs. 14, 15, 16, 17. Diameter of cell (without bristles) about ^-^qq 
to -^^qq" from end to end, including the bristles about -yjjq to yyoo^'* 
In moor pools, Counties Dublin, Wicklow, and Galway. 
Of the genus Tetrapedia and the two original species therein included 
b}^ him, Professor Reinsch has furnished in his work only the diagnosis 
(previously herein repeated), and the explanation of the figures, whence 
we can draw information or gain a knowledge of his views. His figures 
are given in the original upon a very large scale indeed, and hence pro- 
bably calculated to induce misconception as to the actually very minute 
size of the forms ; the majority of them are here reproduced upon a 
scale of some 400 diameters and the best " explanation of the figures " 
* See note, ante, p. 304, 
