212 BRITISH DESMIDTE^E. 



22. E. cr'envlatiim (Ehr.). 



Euastrum crenulatum, Ehrenberg, Meteorp. t. 1. f. 16. Kiitziug, Phyco- 

 logia Germanica, p. 135. 



Germany, Ehrenhery . 



I am unacquainted with the characters of this species. 



COSxMARlUM, Corda. 



34. C. Palanyula (Breb.). 



Cosmarium Palanyula, Brebisson, in lit. cum icone (1846). 

 Falaise, Brebisson. 



M. de Bre'bisson informs me that " Le Cosmarium Palanyula me semble se 

 distinguer du Cos. Cucurhita par sa forme plus cylindrique, tronque'e et non 

 en Conrye, ses scries de points plus fines, transverses et non longitudinales." 

 I am however unable to distinguish this species from C. Cucurhita, for the 

 puncta are scattered in British specimens of the latter. 



35. C. lagenarium (Corda) ; segments triangular, all the angles 

 broadly rounded. 



Cosmarium layenarium, Corda, Aim. de Carlsbad 1835, p. 121, t. 2. f. 26. 

 Brebisson, in lit. 



Carlsbad, Corda. 



36. C Papilio (Menegh.) ; segments smooth, triangular, with rectan- 

 gular apex ; end view linear, with a lobe at the middle of each side. 



Cosmarium Papilio, Meneghini, Consp. Alg. Euyan. p. 18 (1837) ; Synop, 

 Besmid. in Linncea 1840, p. 223. 



Italy, Meneyhini. 



3/. C. ventricosum (Kiitz.). 



C. ventricosum, Kiitzing, Phycoloyia Germanica, p. 136 (1845) ; in lit. cum 

 icone. 



I believe this to be a species of Cosmarium in a dividing state. 



XANTHIDIUM, Ehr. 



7. X. Artiscon (Ehr.); segments narrowed at the base; end margin 

 with numerous elongated spines which are divided at the apex. 



Xanthidium, No. 2, Bailey, American Jovrnal of Science and Arts, v. 41. 



p. 291. t. 1. f. 15 (1841). 

 Xanthidium Artiscon, Ehrenberg, Verhreituny und Einjluss des MikrosJw- 



pischen Lebens in Siid- und Nord-Amerika (1843). 



West Point, New York, Bailey. 



