78 BE1TISH DESMIDIACE.E. 



ENGLAND.- -Tunbridge Wells, Sussex (Jenner; YiW/ 

 Button Park, Warwick (Wills). 



SCOTLAND. Several localities in Aberdeenshire (L'</ 

 A- liixsett). Ben Nevis, Inverness ! Xew Galloway, 

 Kirkcudbright ! Zygospores from Dinnet, Aberdeen 

 (Roi/# Bissett). 



IRELAND. Lakes near Recess, G-alway ! 



Geogr. Distribution. Germany. Austria. Xorwav. 

 Sweden. Poland. 



This Desmid requires investigation as the nature of its 

 chloroplasts is unknown. Ealfs states : "I know no character 

 by which to distinguish the usual state of Penium Jenneri 

 from P. Brebissonii. They agree in size and form; in both 

 the arrangement of the endochrome is similar." If the latter 

 statement is correct the plant should be placed in the genus 

 Cylindrocystis } lont as we have never seen any living specimens 

 we retain it in the genus Peniuvi. 



The conjugation, which takes place by the protrusion of 

 cunjugating-tubes, and the globular zygospore, indicate that it 

 is a plant quite distinct from Cylindrocystis Brebissonii. Per- 

 haps it would be better placed as Cylindrocystis Jenneri nob. 



4. Penium spinospermum Josh. 

 (PL VIII, figs. 6, 7.) 



Penium spinospermum Josh. Notes Brit. Desm. II, 1883, p. '292-. Now and 

 rare Desm. 1885, p. 35, t. 254, f. 10; Cooke, Brit. Desm. LSN;. p. i:>, 

 t. 17, f. 9; De Toni, Syll. Alg. 1889, p. 863; Nordst. Index Desmid. 

 1890, p. '2X1 ; West & G. S. West, Alga-fl. Yorks. 19()O, p. -io. 



Penium spinospermum forma minor West & Gr. S. West, Freshw. Alg. 

 Ceylon, 1902, p. 135, t. 18, f. 8, 9. 



Cells small, 2-2^ times longer than their diameter, 

 unconstricted or with a very slight median constriction, 

 very slightly attenuated towards the apices, which are 

 rounded ; cell-wall smooth. 



Zygospore globose, covered with obtuse conical 

 projections. 



Length 25-30 /t ; breadth 12 - 3-15'5 /n; diameter of 

 /ygospore with projections 2633 /u. 



ENGLAND. Cowgill Wold Moss, AViddale Fell, W. 

 Yorkshire (with zygospores) ! 



