STAUKASTKUM. 177 



of semicells somewhat smaller, angles more produced and 

 cylindrical (almost forming cylindrical processes), with about 

 four rings of minute granules. Length ] 8-20 n ; breadth 

 18-23)u; breadth of isthmus 7 /t . (PL CXXVI, fig. 19). 

 ib. Central China. Central Africa. 



Var. EXTENSUM (Borge) nob. St. dilatatum Ehrenb. var. 

 ion Borge, Beitrage Alg. Schweden, 1906, p. 46, t. 3, 

 f. 37. Basal portion of semicells narrower and almost 

 shortly cylindrical, causing the angles to appear more pro- 

 duced ; granules arranged in 5 or 6 rings around each angle. 

 Length 23-24 ju; breadth 19'5ju; breadth of isthmus 6'5/z. 

 (PI. CXXVI, fig. 17). Distrib. Sweden. 



We have given figures of both the above varieties in order 

 to render clearer the characters of St. disputatum. The 

 br<>ad, fiat apex, and the restriction of the grannies to the 

 circle* around the angles, are its distinctive features. 



St. moniliferum Playfair ('New or Less-known Desm. N". S. 

 Wales/ 1907, p. 188, t. 5, f. 7) and St. campanulatum Playfair 

 (I.e. p. 189, t. 5, f. 8) may both be forms of this Desmid but 

 at present they are insufficiently known. 



34. Staurastrum striolatum (Nag.) Arch. 

 (PI. CXXVII, figs. 1-5.) - 



Phycastrwn (Ambly actinium) striolatum Nag. Gatt. eiuzell. Alg-. 1849, 



p. 126, t. 8 A, fig. 3. 

 Staurastrum striolatum (Nag.) Arch, in Pritch. Infus. 1861, p. 740 ; 



Eabenli. Flor. Europ. Alg. Ill, 1868, p. 201; Nordst. Desm. Brasil. 



1870, p. 225, t. 4, f. 45 ; Wittr. Gotl. Ol. sotv. Alg. 1872, p. 52 ; Kirchn. 



Alg. Schles. 1878, p. 164 ; ? Wolle, Desm. U. S. 1884, p. 126, t. 51, f. 27, 



28; Lagerh. Bidr. Amerik. Desm.-fl. 1885, p. 246; Cooke, Brit. Desm. 



1887, p. 158, t. 54, f. 4 [figures poor"! ; De Toni, Syll. Alg. 1889, p. 1188 ; 



West, Alg. W. Ireland, 1892, p. 178"; Nordst. Index Desm. 1896, p. 243 ; 



Cushman, in Bull. Torr. Bot. Club, 1905, p. 552 ; in Ehodora, 1905, 



p. 264 ; Borge, Beitiage Alg. Schweden, 1906, p. 43 ; Gr. S. West, Alg. 



Yaii Yean, 1909, pp. 38, 69, t. 6, f . 10-12... 



St. striolatum var. celandlcum Wittr. Grotl. Ol. s5tv. Alg. 1872, p. 52. 

 St. striolatum forma brnsiliensis Turn Freshw. Alg. E. India, 1893, p. 109, t. 



13, f . 15 [figures poor] ; W. & Gr. S. West, Some Desm. U. S. 1898, p. 313. 

 St. dilatatum var. indicinn Turn. 1. c. t. 13, f. 17 [figure poor]. 



Cells small, about as long as broad; deeply con- 

 stricted, sinus widely open, rather obtuse at the 

 extremity ; semicells somewhat oblong-elliptic, dorsal 

 margin (apex) straight or slightly retuse, ventral 

 margin convex and inflated in the middle, lateral 

 angles rounded or subtruncate. Vertical view trian- 

 gular, sides concave, angles rounded or subtruncate. 



VOL. iv. 12 



