Staurastrum] xi. desmidiace^ (West). 359 



HuiLLA. — In uliginosis editioribus prope Humpata, Empalanca et 

 LopoUo ; May 1860. No. 15. Etiam Morro de Lopollo ; May 1860. 

 No. 182. 



This Staurastrum belongs to the same section as S. quadricornutum 

 Roy & Biss. and S. gcmelliparum Nordst., but is very distinct from 

 either. Each of the three angles of the semi-cells is more or less 

 quadrate with a short bifurcate process at the two upper corners, 

 with an emarginate wart at each of the lower corners, and a short 

 stout spine between the two emarginate warts. 



6. S. tridens-Neptuni W. et G. S. West in Journ. Bot. 1897, 

 p. 177, t. 369, f. 7. 



HuiLLA. — Freq. in paludibus exsiccandis ; April 1860. No. 176. 

 Etiam inter JJtriculariam, Morro de Lopollo ; April 1860. No. 179. 



The nearest species to this is S. suhtrifurcatum W. et G. S. West 

 [in Trans. Linn. Soc. 2ud ser. v. 258-9, t. xvi. f. 24 (1896)], from 

 which it is distinguished by the three diverging and somewhat shorter 

 spines at each angle being situated in a vertical plane, and in the 

 pentagonal vertical view with acute angles. 



7. S. pentateuehophorum W. et G. S. West in Journ. Bot. 1897, 

 p. 178, t. 369, f. 6. 



HuiLLA. — Freq. in paludibus exsiccandis ; April 1860. No. 176. 

 Etiam freq. inter Utriculariam, Morro de Lopollo ; April 1860. 

 No. 179. 



This species is somewhat allied to S. tridens-Neptuni, but is very 

 distinct from it. 



8. S. heteroplophorum W. et G. S. West in Journ. Bot. 1897, 

 p. 178, t. 369, f. 8. 



HuiLLA. — Freq. in paludibus exsiccandis ; April 1860. No. 176. 

 Etiam inter Utriculariam, Morro de Lopollo ; April 1860. No. 179. 



The arrangement of the spines on the much narrower angles (as 

 seen in vertical view) easily distinguishes this species from S. HyMri.e, 

 Ealfs. At each angle there are two large spines in a vertical plane, 

 and about six much smaller ones round them ; the latter are some- 

 times regularly disposed in a circle round the two larger ones. 



Var. latum W. et G. S. West in Journ. Bot. 1897, p. 178, 

 t. 369, f. 9. 

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



9. S. Pseudohystrix W. et G. S. West in Journ. Bot. 1897, 

 p. 178, t. 369, f. 10. 



HuiLLA. — In paludibus exsiccandis ; Apiil 1860. No. 176. Etiam 

 inter Utriculariam, Morro de Lopollo ; April 1860. No. 179. 



This species differs from S. Hystrix Ralfs in its smaller size, its 

 more angular semicells, its fewer, longer, thinner, and curved spines 

 which are confined to the face of the truncate angles. 



10. S. Welwitschii W. et G. S. West in Journ. Bot. 1897, 

 p. 179, t. 369, f. 1. 



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

 This is a very characteristic species. 



11. S. Corbula W. et G. S. West in Journ. Bot. 1897, p. 179, 

 t. 369, f. 2. 



