380 DESMIDE^. 



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

 pi. xli. fig. 5.; Ralfs, 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. Desmicl. in Linn^ea, 1840, p. 222. 



Hah. 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. EUASTRUM OBLONGUM Ralfs. 



Plate XCI. Fig. 1. 



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

 times longer than hroad. Segments in front view Jive- 

 lohed, semi' oval ; lobes hroad, suhcuneate, emarginate : in 

 lateral view pyramidal, furnished ivith six tuhercles 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 ohlonga 

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

 marium ohlongum Menegh., 1. c. p. 221. Eutomia ohlonga 

 Harv., Man. Br. Al. p. 188. ; Kalfs, in Annals, voh xiv. 

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

 p. 198. 



Hah. Bogs at Fisher's Castle ; Kusthall Common ; War- 

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

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

 Hi^h 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 hroad, suh quadrilateral, 



