/i 



GOMPHONEMA. 423 



b. Lateral surfaces not constricted below the apex, 



4. GOMPHONEMA CRISTATUM Ralfs. 



Plate C. Fig. 1. 



Char. Frustules crested, not consti^icted below the apex, striated 

 laterally. 



Gomphonema cristatum Ralfs, in Annals, vol. xii. p. 463. 

 pi. xviii. fig. 6. ; Jenner, in loc. cit. p. 206. 



Hab. On Conferva glomerata in a stream near Shoreliani, 

 Kent, Dec. 1842. Farnham, Surrey : Mr. Jenner. 



The only species with which this beautiful Gomphonema /^y 

 could be confounded is G. acuminatum, from which it differs 

 in being altogether a smaller plant, and in the absence of the 

 constriction below the apex. 



For its discovery naturalists are indebted to Mr. Jenner. 



5. Gomphonema dichotomum Kidz. 

 Plate XCIX. Fig. 2. 



Char. Frustules linear, cuneate in front view, loith very minute 

 terminal puncta. Lateral surfaces lanceolate, faintly 

 striated. 



Klitz. Synops. Diatom, p. 569. fig. 48. ; Ralfs, in Annals, 

 vol. xii. p. 463. pi. xviii. fig. 7. Gomph. gracile Ehr., 

 Die Infus. p. 217. t. 18. fig. 3. ; Pritch. Infus. p. 227. 

 G. angustum ? Ag., 1831. 



Hab. Trengwainton ponds, near Penzance : Mr. Ralfs. 



The frustules of this species somewhat resemble those of 

 Gomphonema Berkeleyi, but they are more elongated, nar- 

 rower, often nearly linear, and their lateral surface lanceolate, 

 and not clavate. 



6. Gomphonema Berkeleyi Grev. 



Plate C. Fig. 2. 

 Char. Frond forming large mucous masses. Stipes branched, 



E E 4 



"^v 



