216 CYSTIPHORE. 
“So far as our acquaintance with these little Algz reaches, there appear 
to exist four (if not five) distinct, yet kindred forms of figured ‘ Chroo- 
coccacez ’"—their remarkable shapes preclude their being regarded as 
* Lichen-gonidia,’ but whether mature plants or stages in the growth of 
any more complicated structure remains a problem. Ours are at least 
forms which here and there recur, and one can at once recognise them as 
always offering the same charactersitics and as maintaining their apparent 
individuality. Whether they are ‘species’ or not, it may be a matter 
of convenience, should observers meet them elsewhere, and be able to 
throw a light upon them, to have at least a means of their recognition ; 
for these reasons it occurs to me as desirable to record them under 
Reinsch’s genus.”"— W. Archer in Grevillea 1., p. 44. 
Tetrapedia Crux-Michaeli. Reinsch Alg. Mitt. Frank. 
Cells quadrate, lateral margins entire, with two shallow con- 
cavities, each extending half the length of the side, thus pro- 
ducing an obtuse-angled central prominence, deeply incised at 
the angles, incisions diagonal, rectilineal, deep, acute below, 
slightly expanding upwards, thus bisecting the angles, and 
dividing the cell into four broadly cuneate segments, the upper 
angles of which are subacute (the incisions ultimately com- 
pleted, and the cell breaking up?) ; in side view lanceolate, 
ends acute. 
Size. Cells ‘008-012 mm. diam. 
Archer in Grevillea i., p.45. Reinsch Algenflora, t. i., fig. 6. 
In running water (very scantily) near Mullingar,. Co. West- 
meath, Ireland. 
Plate LXXXVII. fig. 8. Cells magnified 600 diam. 
Tetrapedia Reinschiana. Archer in Grevillea L, p. 46, t. 3, f. 
11-18. 
Cells quadrangular, two opposite margins excavated by a 
wide triangular sinus, thus subdividing the cell into two broadly 
cuneate segments connected by a wide isthmus, and somewhat 
convex on their lower margins ; the other two opposite margins 
of the cell, that is the upper margins of the segments, very 
slightly concave at the middle, somewhat raised towards the 
acute outer angles; in side view oblong, constricted at the 
middle, ends rounded. 
Size. Largest cell :0075-'01 mm. diam. 
In moor pools, Co. Dublin and Wicklow. 
Plate LXXXVII. fig.9. Cells magnified 600 diam. 
Tetrapedia setigera. Archer in Grevillea 1, p. 46, t. 3, fig. 14-17. 
Cells triangular, the lateral margins somewhat deeply ex- 
cavated by a broad rounded sinus dividing the cell into three 
