EUASTRUM. 381 



compressed, dotted. Segments in front view three-lobed ; 

 lateral lobes each twice slightly emarginate : in lateral view 

 much compressed. 



Cosmarium Pelta Corda, Almanac de Carlsbad, p. 121. C. 

 Pelta Menegli., Synops. Desmid. p. 222. Euastrum 

 Pelta Kalfs, in Annals, vol. xiv. pi. vii. f. 1. ; Jenner, 

 loc cit. p. 198. 



Hab. Bogs at Fisher's Castle and on Ashdown Forest ; 

 Piltdown Common : Mr. Jenner. Dolgelly ; Penzance : 

 Mr. Ralfs. High Beech : A. H. H. 



There is no other species with ^vhich this need be con- 

 trasted. 



4. Euastrum Didelta Ralfs. 



Plate XC. Fig. 8., and Plate XCI. Fig. 11. 



Char. Frond about three times as long as broad, dotted. 

 Segments in front view pyramidal, and laterally usually 

 twice emarginate; in irvLUSYerse somewhat four-lobed, and 

 in end view oval. 



Heterocarpella Didelta T urp. , Mem. p.295.(1828). Hetero^ 

 carpella polymorpha^\\tz., Synops. Diatom, in Linn^ea, 

 1833, p. 70. fig. 82. Euastrum ansatum, Abhandl. d. 

 Akademie Wissensch. zu Berlin, 1831, p. 82.; Ehr. 

 Infus. p. 162. t. 12. fig. 6. Cosmarium lagenarium, Al- 

 manac de Carlsbad, 1835, p. 206. pi. ii. fig. 26. Cos- 

 marium Didelta Menegh., 1. c. p. 219. Euastrum Didelta 

 Palfs, in Annals, vol. xiv. pi. vii. fig. 2. ; Jenner, in Flora 

 of Tunbridge Wells, p. 198, 



Hab. Frequent in Sussex : Mr. Jenner. Henfield : Mr. 

 Borrer. Cheshunt : A. H. H. Barmouth Boad : Rev. 

 T. Salwey. Caernarvon ; Dolgelly, near Carmarthen ; 

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



A very distinct species. 



