360 xi. desmidiace/E (West). [Staurastrum 
Huilla. — In paludibus 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 Lopollo ; Feb. I860. No. 192. 
12. S. actinotum W. et G. S. West in Journ. Bot. 1897, p. 180, 
t. 369, f. 4. 
Huilla. — In paludibus exsiccandis ; April 18(30. Xo. 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 Utricular lam, Morro de Lopollo; April 1860. 
Xo. 179. 
13. S. cassidum W. et G. S. West in Journ. Bot. 1897, p. 180, 
t. 368, f. 21. 
Huilla. — In uliginosis editioribus prope Humpata, Empalanca et 
Lopollo ; May 1860. Xo. 15. 
This species is distinguished from S. trihedrale Wolle (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 
G. S. West (I.e. f. 30) seems to be intermediate in form between this 
species and S. 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 Utricidariam, Morro de Lopollo ; April 1860. 
Xo. 179. 
This is very distinct from S. coxmarioidea Xordst. [in Vidensk. 
Medd. f. d. naturh. Foren. (1869), no. 14-15, 223, t. iv. f. 43 (1870) ], 
and it is different 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 6'. 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 different basal angles and a very different sinus. 
15. S. scrohiculatum W. et G. S. West in Journ. Bot. 1897, 
p. 181, t. 368, f. 18. 
Huilla. — In uliginosis editioribus prope Humpata, Empalanca et 
Lopollo ; May I860. Xo. 15. 
