22 BRITISH DESMIDIACE^E. 



interesting as being the only species of the C. conspersum- 

 group of which the zygospore is known. This spore is smooth 

 and globular (vide West, ' Freshw. Alg. Maine ' II, 1891, 

 p. 355, t. 315, f. 10). 



233. Cosmarium Pseudobroomei Wolle. 

 (PI. C, figs. 7, 8; PI. CIII, fig. 7.) 



Cosmarium Broomei Ralfs, Brit. Desm. 1848 [in part], t. 33, f. 7. 



C. Pseudobroomei Wolle in Bull. Torr. Hot. Club, 1884, p. 16, t. 44, f. 30,. 

 37 ; Desm. U. S. 1884, p. 86, t. 51, f. 36, 37 ; Turner, Freshw. Alg. E. 

 India, 1893, p. 66, t. 9, f. 41 ; Nordst. Index Desm. 1896, p. 208 ; Borge, 

 Austral. Siisswasserchlor. 1896, p. 20, t. 3, f. 34 ; Borge, Trop. u. sub- 

 trop. Siissw.-Chlor. 1899, p. 20, t. 1, f. 22; Lutkem. Desm. Central 

 China, 1900, p. 119 ; W. G. S. West, Freshw. Alg. Ceylon, 1902, p. 170; 

 Gutw. Alg. Ins. Java, 1902, p. 601 ; G. S. West, Alg. Third Tanganyika 

 Expedit, 1907, p. 123. 



Cells small, about as long as broad, very deeply 

 constricted, sinus narrowly linear with a slightly 

 dilated extremity : semicells oblong-rectangular with 



i' O O 



the angles slightly rounded, sides very slightly convex, 

 apex straight or very slightly convex. Side view of 

 semicell subcircular. Vertical view oblong, with sub- 

 parallel sides and broadly rounded extremities. Cell- 

 wall densely granulate ; granules small and solid, 

 arranged in decussating oblique series and in somewhat 

 less distinct vertical series (as in C. Quadmm),fron\ 23 

 to 32 showing at the margin of a semicell. Chloro- 



O O 



plasts axile, with two pyrenoids in each semicell. 



Zygospore subglobose and smooth. 



Length 33-38 //, ; breadth 29-30 ^ ; breadth of 

 isthmus 8'5-12 ^ ; thickness 16-17'5 JJL. 



WALES. Capel Curig and Llyn-y-cwm-ffynon, Car- 

 narvonshire ! 



Geor/r. Distribution.- -GalicisL in Austria. Central 

 China. India. Ceylon. Java. Madagascar (var.). 

 E. Africa (var.). Central Africa. United States. Brazil. 



There is little doubt that the zygospore figured by Ralfs on 

 his supplementary plate 33 under the name of "C. Broomei' 

 is that of C. Pseudobroomei. The latter is distinguished from 

 C. Broomei hy the entire absence of a median inflation in the 

 vertical view, and hy its somewhat coarser granulation. 



C. Pseudobroomei approaches very closely the smaller forms 



