r FA i CM. 



. Kerry! Galwa y ! Donegal! Dublin and 

 Wicklow (Archer). Down! Antrim! 



Geogr. Jiixtrtlintioii. France. Germany. Austria. 

 Norway. Sweden. Italy. United States. 



Ralfs believed this species to be minutely and indistinctly 

 punctate, and we find the punctulations very variable in 

 intensity; some forms are very distinctly punctate, but others 

 are apparently quite smooth. 



B. 



10. Penium margaritaceum (Elirenb.) Breb. 

 (PL VIII, figs. 32-35.) 



Closterium margaritaceum Ehrenb. Infus. 1838, p. 95, t. 6, f. xiii; Hass. 

 Brit. Freshw. Alg. 1845, p. 376, t. 88, f . 5. 



Penium margaritaceum (Ehrenb.) Breb. in Ealfs' Brit, Desni. 1S4S, p. 149, 

 t. 25, f . 1 a, b, c t. 33, f. 3 ; Arch, in Pritch. Infus. 1861, p. 75U, t. 2, 

 f. 14, 15 ; Eabenh. Flor. Em-op. Algar. Ill, 1868, p. 121 ; Kirchn. Alg. 

 Schles. 1878, p. 135; Wolle, Desui. U.S. 1884, p. 34, t. 5, f. 5, 6, 11; 

 Cooke, Brit. Desm. 1886, p. 38, t. 17, f. 1 a-g ; West, Alg. W. Ireland, 

 1892, p. 126; Alg. Enq-. Lake Distr. 1892, p. 720; Nordst. Index 

 Desmid. 1896, p. 164; West & G. S. West, Alg. S. England, 1897, 

 p. 478 ; Alga-fl. Yorks. 1901, p. 46 ; Alg. N. Ireland, 1902, p. 21 ; Roy 

 & Biss. Scott. Desm. 1894, p. 252. 



Cylindrocystis margaritacea Reinsch, Algenfl. Frank. 1867, p. 198. 



f Penium pandurans De Not. Desm. Ital. 1867, p. 70, t. 8, f. 80. 



Cells large, 6-12 times longer than their diameter, 

 cylindrical or subfusiform, with a distinct median con- 

 striction, apices truncately rounded ; cell- wall reddish- 

 brown in colour and furnished with longitudinal rows 

 of granules ; chloroplast with, about 10 longitudinal 

 plates (or ridges) and often showing a slight median 

 interruption. 



Zygospore globose and smooth. 



Length 73-1 70 /t; breadth 12'5-20/u; breadth of 

 apices about 7*5-18 /*; diain. zygosp. 47 /u. 



ENGLAND. Westmoreland! (Bissett). AV. and X. 

 Yorks! Lancashire! Cheshire (/('"//). Warwick 

 (1I7//.S). Gloucester (Half*). Surrey! Sussex (Ea//s). 

 Hants! (AV//x). Devon! Cornwall! (Halfs). Essex! 



(Ealfs). 



WALES. General, but scarce ! 



