COSMARIUM. 117 



Cells very large, about twice as long as broad, 

 slightly constricted, sinus a shallow depression ; semi- 

 cells widely ovate from a broad base, apex sub- 

 truncately rounded ; cell-wall somewhat sparsely 

 punctate. Vertical view circular. 



Zy go spore unknown. 



Length 140-1 50 /i; breadth 66-74^; breadth of 

 isthmus 60-64 p.. 



Geogr. Distribution.- -India. 



The typical form of this species is not known to occur in 

 the British Islands. It differs from C. turgidum in its some- 

 what smaller size, its more rounded semicells, and less truncate 

 apices. 



Forma minor Sclimidle. (PI. LXXIV, figs. 22, 23.) 



C. subturgidum forma minor Schmidle, Alg. aus Sumatra, 1895, p. 300, 



t. 4, f . 2 ; West & G-. S. West, Freshw. Clilor. Koh Chang, 1901, p. 92. 

 Pleurotseniopsis subturgida (Turn.) Schmidle var. minor Schmidle, Siiss- 

 \vasseralg. Austral. 1896, p. 305. 



A smaller variety, slightly less constricted than the 

 type ; semicells with slightly broader apices (more as 

 in C. turgidum) which are sometimes very faintly 

 retuse in the middle. Chloroplasts parietal, 4-5 in 

 each semicell in the form of longitudinal bands, with 

 several pyrenoids. 



Length 88-120 //,; breadth 52-64^ ; breadth of 

 isthmus 4959 JJL. 



IRELAND.- -Small lakes between Clifden and Round- 

 stone, Gal way ! 



Geogr. Distribution.- - Siam. Sumatra. Samoa. 

 Australia. E. Africa. 



Schmidle describes what he considers to be the zygospore 

 of this form from Australia. It is globose and furnished 

 with rather long, slightly curved, and blunt spines. From 

 his stated dimensions (cliam. 27 /x; spines about 10 ILL in 

 length), however, we do not see how the zygospore can 

 belong to a Desmid at all approaching C. subturgidum f . minor 

 in size. 



E. African forms are recorded by Schmidle as only 66 /LI in 

 length and 86/1 in breadth. 



