406 MR. G. S, WEST ON 
Another series of species which has been confused with that 
including Staurastrum aculeatum is the one which is constitated 
by S. margaritaceum, Menegh., S. sexcostatum, Bréb., and their 
derivatives. Certain forms derived from 8. seacostatum have 
most certainly acquired a resemblance to a few extreme forms of 
S. aculeatum; but this fact, in my opinion, is not owing to 
direct specifie relationship, but rather to parallelism of modifica- 
tion along two totally different lines of evolution. The following 
table may better illustrate the idea that I intend to convey :— 
S, PstUDOSEBALO! Witte 
DG Grënn REINSCH. 
S.MaroariTaceum NMeuteu. 
D SEBALOI vAR.ALTUM West & G.S West 
S. AuaTiNUM, Cooke X Wiis. S, MaRGARITACEUM varst 
S.Vestitum Rates. 
LN 
SVestitum VAR SEMIVESTITUM WE 
"D StxcosraruM Bree. 
A ACULEATUM Mentis MER Stcosrasum Der LSK West. 
3, D FORMA Sow? LUN (d Ts han. v. Tue F Senn o Bari] 7 
tn 
S,Controversum Grea. n 
^s. Acuceatum Var ÜnuaruM Nonosr. -----....-.. Le eee 
H 
ü 
S. AncricuM Noe .$ 00007 | 
| 
| 
j 
IE AcuL v. ORNATUM F. SPINDSISSIMA m 
| 
| 
| d Acuı.V.Derauperatum Wiuuc) 
* W. Schmidle in * Hedwigia,’ 1895, t. i. f. 22. 
t Cfr. S. margaritaceum var. figured by West in Journ. Roy. Mier. Soe. 
1890, t. 6, f. 32. 
t S. aculeatum var. ornatum, Nordst. f. simpler, Boldt, is unquestionably a 
form of S. sercostafum subsp. productum, West, in Journ. Roy. Mier, Soc. 
1892, p. 733, t. 9. f. 34. 
$ S. arcricum nob. includes S. aculeatum var. ornatum, Nordst., f. spinosissima, 
Wille (in Ofvers. af K. Vet.-Akad. Förh. 1879, no. 5, p. 54, t. 13. ff. 67-68), 
and probably S, aculeatum var. depauperatum, Wille (J. c. p. 55, t. 13. f. 69). 
The name ‘ spinosissimum’ could not be adopted, as there is a S. spinosissimum, 
W. B. Turner. 
