118 BRITISH DESMIDIACE^E. 



126. Cosmarium attenuatum Breb. 

 (PL LXXIV, figs. 24, 25.) 



Cosmarium attenuatum Breb. in Ralfs' Brit. Desm. 1848., p. 110, t. 17, 

 f . 9 ; Arch, in Pritch. Infus. 1861, p. 735 ; Wittr. Skandinav. Desm. 

 1869, p. 15 ; Boy & Biss. Scott. Desm. 1894, p. 42 ; Nordst. Index 

 Desm. 1896, p. 54 ; West & G. S. West, Alga-fl. Yorks. 1900, p. 95. 



Calocylindrus attenuatus Cooke, Brit. Desm. 1887, p. 127, t. 43, f. 12. 

 [Not Calocylindrus attenuatus Racib. in Spraw. Kom. fizyjogr. Akad. 

 Umiej. Krakow, xix, 1884, p. 9 == Cosmarium elongatum E-acib. 1885.] 



Dysphinctium attenuatum Turn. Freshw. Alg. of E. India, 1893, p. 44. 



Cells rather small, about 2-J times as long as broad, 

 slightly constricted, sinus a shallow notch (generally 

 rounded) ; semicells attenuate-ovate, apex narrow and 

 rounded, not infrequently faintly retuse at the extre- 

 mity. Vertical view circular. Cell-wall sparsely 

 punctate. Chloroplasts axile, . . . ? 



Zy go spore unknown. 



Length 62-64 ^; breadth 20-2 7 /x; breadth of 

 isthmus, 17'5-19'5 p.. 



ENGLAND. - Arncliffe and Cowgill Wold Moss, 

 Widdale Fell, W. Yorks ! Mickle Fell, N. Yorks ! 

 Near Bristol, Gloucestershire (Thwaites). Near Bovey 

 Tracey, Devon (Bennett). 



WALES.- -Near Swansea, Glamorgan shire (Rolfs). 



SCOTLAND.- -Brin, Inverness (Hoy fy Bissett). 



Geogr. Distribution. France. Norway. Spitzbergen. 

 India. 



In external form this species more nearly resembles Penium 

 curium than any other Desnrid. Its semicells are,, however, 

 more attenuated,, and the cell-wall is differently punctated. 

 Ralfs states that it differs chiefly from Penium curium in the 

 chloroplasts, but he neither describes nor figures this 

 difference, and we have only examined preserved empty 

 cells. 



ADDENDA TO THE SMOOTH G08MAEIA. 



127. Cosmarium orthogonum Delp. 



(PL LXVI, figs. 13, 14.) 



Cosmarium orthogonum Delp. Desm. siibalpin. 1877, p. 8, t. 7, f. 49-51 

 ["ortogonum"']-, De Toni, Syll. Alg. 1889, p. 1006 ; Eoy & Biss. Scott. 

 Desm. 1894, p. 170 ; Nordst. Index Desm. 1896, p. 191. 



Ursinella orthogona Kuntze, Eevis. gen. plant. 1891, p. 925. 



