16 26 Proceedings of the Royal Irish Academy. 



Scenedesmus obliquus (Turp.) Kiitz. — CI, VL, W, Cn ; C, in one place small 

 forms with cells 7'2 x 2 - 5/*. 



var. dimorphus (Turp.) Eabenh. — K, VL, DL, D ; Cr, length of 

 cells 24-26/j., width of colony of 4 cells with processes 

 26-30/x, width of colony of 4 cells at middle 21/x ; W ; 

 C, length of cells 20-8-2L5/*, width of colony of 4 cells with 

 processes 23'3yu., width of colony of 4 cells at middle 15-5/*. 

 quadricauda (Turp.) Breb.— 0, EL, I, LG, L, CI, VL, DL, WD, Cr. 

 var. horridus Kirchn. — Mw, C. 

 Dimorphococcus hmatus A. Br. — M, C. 

 Selenastrum gracile Beinsch. — D, Cr, W. 

 Ankistrodesmus falcatus (Corda) Ealfs.— C, L, DL, SL, CI, W, B, Cr, K. 



var. tumidus G-. S. West.— C, in several places up to 6/x broad ; 



Cr, up to 7'5/x broad. 

 var. acicularis (A. Br.) G. S. West.— C, J, SI, CL. 

 var. mirabilis (W. & G. S. West) G. S. West.— W, 91 x 3 ft 

 slightly curved, chloroplast interrupted ; C, 133 x 3'5[t, 

 almost straight. 

 Pfitzeri (Schrod.) G. S. West.— C, Mw, CI. 

 *Braunii (Nag.) W. & G. S. West.— Cr. 

 convolutus Corda var. minutum (Nag.). — Cr, C. 



SELENASTRUM sp. now — Cellulae semilunatae, apicibus acutis, inter 

 apices lS-lS'S^., lat. ad medium 7'5yu. Inter algis variis (Cosmariis, 

 &c). Cr. 

 Closteriopsis longissima Lemm. — I, CI, LG, D. 



Reinschiella CITRVATA sp. nov — B, cellulis solitariis, libere natantibus, late 

 lunatis, margine interiori concavo, apicibus acutis, spina brevi extror- 

 sum curvata praeditis, long, sine spin., 38/t, lat. 20/x, long. spin. 5 -6/*. 



C. (Bl. I, fig. 2.) 



Kirchneriella obesa (Westj Schmidle. — K ; plankton of BL, VL, L, Cr. 



Sub-fam. Oocystideae. 

 *Oocystis crassa Wittr. — B, Cr, SL, D. 

 gigas Arch. — I. 



lacustris Chod. — Plankton of LG. 

 solitaria Wittr. — C, 19 x 10^, also in other places 34 x 20^, 33 x 21-5 ; 



D, up to 33-5 x 21-Ofi; M, I, B, M ; CB, 35 x 20^ (average) : this 

 often occurred in fair abundance of constantly small dimensions 

 often 8-9/a broad and 14-16/y. long; some examples from neighbouring 

 pools were larger, extra broad, 30-31 x 225/x ; Cr, 23-28 x 145-17/x. 



