COSMARIUM. 73 



observed by Archer, Joshua, and Roy, but as these authors 

 have not published figures of them, and we ourselves have 

 never observed them, we are unfortunately only able to o-ive a 

 description of them. C. truncatellum sometimes occurs in 

 considerable quantity amongst submerged 



94. Cosmarium subcapitulum West. 

 (PI. LXXII, fig. 17.) 



Cosmarium subcapitulum West, Alg. Engl. Lake Distr. 1892, p. 725, t. 9, 

 f . 20 ; Xordst. Index Desm. 1896, p. 244. 



Cells small, a little broader than long, deeply con- 

 stricted, sinus open, triangular and subacute; semi- 

 cells transversely oblong-hexagonal, upper and lower 

 part of sides converging outwards to form an angle a 

 little less than a right angle, apex broad and very 

 slightly retuse. Side view of semicell circular-elliptic. 

 Vertical view fusiform-elliptic, poles subacute, ratio of 

 axes about 1 : 3. Cell-wall smooth. 



Zygospore unknown. 



Length 17 JJL; breadth 19/x; breadth of isthmus 4/>t; 

 thickness 7' 5 ^. 



ENGLAND. Xear Bowness, Westmoreland ! 



Tli is species differs from C. Capitulum Roy & Biss. (consult 

 page 119) in the truncate and subretuse apices, in the acute 

 lateral angles of the semicells, in the form of the sinus (which 

 is not acuminate), and in the subacute poles of the vertical 

 view. 



95. Cosmarium pygmaeum Arch. 

 (PL LXXI, figs. 22-31.) 



Cosmarium pygmseum Arch, in Quart. Jourii. Micr. Sci. 1864, p. 174, t. 6, 

 f. 45-49; Wittr. Skandinav. Desm. 1869, p. 26; Cooke, Brit. Desm. 

 1886, p. 91, t. 37, f . 8 [figure bad] ; De Toni, Syll. Alg. 1889, p. 1046 ; 

 West, Alg. X. Wales, 1890, p. 288 ; Alg. W. Ireland, 1892, p. 146, t. 20, 

 f. 24; Liitkem. Desui. Attersees, 1893, p. 550; Eoy & Biss. Scott. Desm. 

 1894, p. 173 ; Nordst. Index Desm. 1896, p. 214 ; West & G. S. West, 

 Alg-. S. England, 1897, p. 486 ; Alga.-fl. Yorks. 1900, p. 92: A1-. X. 

 Ireland, 1902, p. 34 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 22. 



Sphferozosma pygmxum Eabenli. Flor. Europ. Alg-. Ill, 1868, p. 15O. 

 This is not " Sphserozosina pygmxum Cooke," Brit. Desm. 1886, p. 5, 

 t. 2, f 5.] 



Cosmarium Schliephackianum Gran, in Rabeiih. Flor. Europ. Alg-. Ill, 



