360 XI. DESMiDiACEiE (West). [Staurastrum 



HuiLLA. — In paludibns exsiccandis ; April 1860. No. 176. 



This species has about twenty-five very short spines on each of 

 the three angles of a semi-cell, over which is placed a pair of slender^ 

 erect and longer spines. It most nearly approaches S. Welwitschii in 

 form and arrangement of spines, but differs from it in being triangular 

 in vertical view, and in having a pair of slender erect spines in place 

 of the single stout spine of the latter species. The angles are also 

 furnished with more numerous and shorter spines, and it is moreover 

 a smaller, much more constricted species. 



Var. pulchrum W. et G. S. West in Journ. Bot. 1897, p. 179, 

 t. 369, f. 3. 



HuiLLA.— In editis de Morro de LopoUo ; Feb. 1860. No. 192. 



12. S. actinotum W. et G. 8. West in Journ. Bot. 1897, p. 180, 

 t. 369, f. 4. 



HuiLLA. — In paludibus exsiccandis ; April 1860. No. 176. 

 This peculiar Staurastrum does not appear to be closely related 

 to any other. 



Var. simplex W. et G. 8. West, I.e., t. 369, f. 5. 

 HuiLLA. — Inter Utriculariam, Morro de LopoUo; April 1860. 

 No. 179. 



13. S. cassidtun W. et G. S. West in Journ. Bot. 1897, p. 180, 

 "t. 368, f. 21. 



HuiLLA. — In uliginosis editioribus prope Humpata, Empalanca et 

 LopoUo ; May 1860. No. 15. 



This species is distinguished from S. triliedrale WoUe (Desm. U.S. 

 123, pi. 40, f. 12-14 ; W. et G. S. West in Trans. Linn. Soc. 2nd ser. 

 V. 260-1, t. xvi. f. 29) by its smaller size, its more conical semi-cells 

 with comparatively broader apices and almost straight sides, by the 

 form of its vertical view, and by the much smaller and more numerous 

 markings on the membrane. S. trihedrale var. rhomboideum W. et. 

 Gr. S. West (I.e. f. 30) seems to be intermediate in form between this 

 species and <i. trihedrale, but it has the characteristic basal angles, the 

 narrow apex, and the markings of S. trihedrale, whereas none of these 

 characters are possessed by S. cassidum. 



14. S. areolatum W. et G. S. West in Journ. Bot. 1897, p. 180,. 

 t. 367, f. 17. 



HuiLLA. — Inter Utrieulariam, Morro de LopoUo ; April 1860- 

 No. 179. 



This is very distinct from S. cosmarioides Nordst. [in Vidensk. 

 Medd. f. d. naturh. Foren. (1869), no. 14-15, 223, t. iv. f. 43 (1870) ], 

 and it is difEerent in the form of its front view and in its membrane 

 from any species of Cosmarium. Borgesen, in Vidensk. Medd. f. d. 

 naturh. Foren., Kjoben. 1890, 50 (1891), figures (under a wrongly 

 stated magnification !) under the name of S. cosmarioides forms which 

 he suggests may be trigonal and tetragonal forms of several species 

 of Cosmarium. His fig. 2 somewhat approaches this species in form, 

 but it has difEerent basal angles and a very difEerent sinus. 



15. S. scrobiculatum W. et G. S. West in Journ. Bot. 1897,. 

 p. 181, t. 368, f. 18. 



HuiLLA. — In uliginosis editioribus prope Humpata, Empalanca et 

 LopoUo ; May 1860. No. 15. 



