380 DESMIDE^. 



zu Berlin, 1833 (1832), p. 247.; Ehr. Infus. p. 162. 

 pi. xii. fig. 5.; Haifa, in Annals, vol. xiv. pi. vi. fig. 3.; 

 Jenner, in Fl. Tunb. Wells, p. 198. ; Pritch. Infus. 

 p. 196. fig. 125. Cosmarium verrucosum Menegh., 

 Synops. Desmid. in Linnaea, 1840, p. 222. 



Hob. Cheshunt : A. H. H. Rusthall Common, and Ash- 

 down Forest : Mr. Jenner. Penzance : Mr. Ralfs. 



This is a very distinct species and the only British one of 

 the genus which has a dentated frond. 



2. EUASTKUM OBLONGUM Ralfs. 



Plate XCI. Fig. 1. 



Char. Frond large, smooth, oblong, oval, dotted, three or four 

 times longer than broad. Segments in front view five- 

 lobed, semi-oval ; lobes broad, subcuneate, emarginate : in 

 lateral view pyramidal, furnished with six tubercles each. 



Euastrum pecten, Abhandl. der Akademie d. Wissensch. zu 

 Berlin, 1831, p. 82. Euastrum pecten Ehr., Infus. p.162. 

 pi. xii. fig. 4. ; Pritch. Infus. p. 196. Echinella oblonga 

 Grev., in Hook. Br. Fl. vol. ii. p. 398. (1830). Cos- 

 marium oblongum Menegh., 1. c. p. 221. Eutomia oblonga 

 Harv., Man. Br. Al. p. 188. ; Ralfs, in Annals, vol. xiv. 

 p. 189. pi. v. fig. 4. ; Jenner, in Fl. Tunbridge Wells, 

 p. 198. 



Hob. Bogs at Fisher's Castle ; Rusthall Common ; War- 

 bleton, &c., Beckley : Mr. Jenner. Penzance, Dolgelly, 

 and Caernarvon : Mr. Ralfs. Aberdeen : Dr. Dickie. 

 High Beech : A. H. H. 



This is the finest species of the genus, and a beautiful 

 microscopic object, as are most of the species of this genus. 



3. EUASTRUM PELTA Ralfs. 



Plate XCI. Fig. 3. 

 Char. Frond three times as long as broad, subquadrilateral, 



