216 BRITISH DESMIDIE.E. 



49. S. senarium, Ehr. 



Besmidium senarium, Ehrenberg, Verbr. xmd Ehifluss des Mikrosk. Lebens in 

 Slid- und Nord-Amerika, t. 4. f. 22 (1843). 



West Point, New York, Bailey. 



Ehrenberg' s figure represents the end \^ew as triangular, the angles termi- 

 nating in short rays, which" are tipped by minute spines : on each side are two 

 short forked spines, and six others on the upper surface. His figure agrees 

 in some respects with Staurastrum spinosum, consequently S. senarium may 

 prove a variety of that very variable species. 



50. S. Ehrenbergii, Corda. 



Xanthidium Ehrenbergii, Corda, Observ. Microscopiques sur les Animalcules 

 de Carlsbad, p. 29. t. 5. f. 36, 3/ (1840). 



Prague, Corda. 



" Corpuscules par paire, vus de cote, ovales ; vus d'en haut, triangulaires, 

 munis de six appendices terminaux et lateraux, et de deux autres appendices 

 centraux, qui sont courts, blancs, en fourchette, mais a pointes divergentes." — 

 Corda, I. c. 



Corda' s figure of the front view resembles Staurastrum spinosum. 



51. S. articulatum, Corda. 



Xanthidivm articulatmn, Corda, Observ. Microscopiques sur les Animalcules 

 de Carlsbad, p. 28. t. 5. f. 35 (1840). 



Carlsbad, Prague and Reichenberg, Corda. 



" Corpuscules ovales, par paire, munis aux deux bouts d'un appendice a 

 deux cellules, qui se divise encore en forme de fourchette ; et lateralement en 

 deux appendices plus longs a quatre cellules, et mie pointe en fourchette. Sur 

 les deux cotes plats, se trouvent deux protuberances transversales, egalement 

 pourvues de deux allongements cellulaires en fourchette." — Corda, /. c. 



52. S. coronatum (Ehr.); end view triangular and terminating at 

 each angle in three short, diverging arms which are divided at the 

 apex. 



Xanthidium, No. 3, Bailev, American Journ. of Science und Arts, v. 41. 



p. 291. t. 1. f. 16 (1841). 

 Xanthiditim coronatum, Ehrenberg, Verbr. und Einjluss des Mikrosk. Lebens 



in Slid- und Nord-Amerika, t. 4. f. 26 (1843). 



West Point, New York, Bailey. 



Professor Bailey's figure, which in a list of American Desmidieee obligingly 

 comnmnicated he refers to as Xanthidium coronatum, Ehr., in the front view 

 resembles Xanthidium Artiscon, whilst Ehrenberg' s ap})ears to me a good 

 representation of the front view oi Didymochidon furciyerus. 1 doubt there- 

 fore whether these two figures can represent the same species. 



