PEDIASTRUM. 389 



3. Pediasthum elegans Hass. 



Plate LXXXVL Fig. 19. 



Char. Frond cii'cular, star-like, cojnjwscd of six marginal 

 cresccntic cells, and two central cells of an angular form. 



Pediastrum Napoleonis Ivalfs, in Annals^ vol. xiv. p. 470. 



pi. xii. fig. 6. 

 Hab. Dolgelly : Mr. Ralfs. 



The above species, described and figured by ]\Ir. Ralfs 

 under the name of Pediastrum Napoleonis, and as the Micra- 

 sterias Napoleonis of Ehrenberg beai'S no resemblance what- 

 ever to the figures given of that species, nor indeed to any 

 of Ehrenbei'g's figures, save a distant one to fig. 5 e. of pi. xi., 

 which is regarded by the author as a state of Micrasterias 

 Boryanum, which it certainly cannot be, as the frond in the 

 figure alluded to is made of ten marginal cresccntic cells, and 

 fi.ve internal angular cells. 



4. Pediastrum Boryanum Menegh. 

 Plate LXXXVL Fig. 13. 



Char. Frond composed usually of two circles of cells, en- 

 closing a central cell, hut sometimes there are three and 

 €vcn four concentric circles, inner circle formed of Jive 

 cells, and seco7id circle of ten. ]Marginal cells deeply bifid. 

 Helierella Boryana Tm-pin, Mem. du Mus. vol. xvi. p. 319. 

 pi. xiii. fig. 22. 1828. Pediastrum simplex, P. duplex, 

 P. biscidiatum INIeyen, Nov. Act. Nat. Cur. xiv. 1829, p. 

 772, 773. t. 3. figs. 7. 13, 14. 16, 17, 18.; Isis, 1830, 

 p. 163. Opharium speciosum, O. forynosissimuyn , et O. ver- 

 ticillatnm Losano, Mem. de Zarino, xxxiii. 1829 ; Isis, 

 1832, p. 768. t. xiv. figs. 17, 18. 21. Micrasterias sim- 

 plex, M. Boryi, M. duplex, et M. Selona^a Kiitzing, Lin- 

 naja, 1833, p. 601. 3. t. xix. fig. 92 b. Euastrtnn 

 pcntangulare ct Pediastrum quadranguni Corda, Almanac 

 de Carlsbad, 1835, p. 206. 7. t. iii. figs. 32. 35. Mi- 

 ce s 



