I'KMl'M. 79 



SCOTLAND. Inverness, Aberdeen, Kincardine, Stir- 

 ling, Argyll, Renfrew (li<>>/ \ Bissett). 



IRELAND. Derrystrasna Bog, Armagh. (Jv#lni). 

 Mourne Mts., Down (with zygospores) ! 



(ii'niji-. Distribution. Ceylon. 



Joshua's measurements for this species are quite wrong 

 according to his own figures; we are therefore compelled to 

 consider the " forma minor " as identical with the typical 

 plant. It is a rare species with a very characteristic zygos] ion-. 



5. Penium didymocarpum Lund. 

 (PL VIII, figs. 11-1:3.) 



Penium didymocarpum Limcl. Desm. Suec. 1871, p. 85, t. 5, f. 9; Coukc, 

 Brit. Desm. 1886, p. 44, t. 17, f. 6 ; Norclst. Freshw. Alg. N. Zeal, isss, 

 p. 72 (formse incertae) ; West, Alg. Eng. Lake Distr. 1892, p. 7i'l ; 

 Liitkem. Desm. Attersees, 1893, p. 545. 



Schizospora minor Eeinsch, Contrib. Alg. et Fung. 1875, p. 87, t, 17, f. L'. 



Schizospora didymocarpa Hansg. Prodr. Algenfl. Bohm. 1888, p. 175 (note) 



Cells small, about 2^ times longer than their dia- 

 meter, miconstricted, subcylindrical, slightly attenuated 

 towards the poles, which are rounded ; cell-wall 

 smooth; each chloroplast with one pyrenoid. 



Zygospore double, compressed, subquadrate with 

 rounded angles, of which the exterior ones slightly 

 project ; empty semicells closely adhering to the ex- 

 terior angles. 



Length 31-38 j; breadth 13-1 5*3 /ij length of zy go- 

 spore 22-30 /u, breadth 31-38 /u. 



ENGLAND. Risley Bog (Roij) ; Hawkshead (with 

 zygospores) ! , Lancashire, Devon (Bennett). Cornwall 

 (Ma/rquand). 



WALES. Capel Curig, Carnarvonshire (Roy). 



SCOTLAND. General ! ; conjugation not uncommon 

 (Roy cj- Bissett). Near Balallan, Lewis, and near Tar- 

 bert, Harris, Outer Hebrides (with zygospores) ! 



IRELAND. Dublin and Wicklow (Archer). 



Geogr. Distribution. Austria. Sweden. Denmark. 

 Lapland. Central China. New Zealand. 



This species is remarkable in the possession of a double 

 zvgospore, a phenomenon which normally exists in about four 



