422 DIATOMACEJE. 



Ehr., Die Infus. ; Jenner, in Flora of Tunbridge Wells, 

 p. 206. 



Hal. On aquatic plants in pools and ditches, near Hen- 

 field : Mr. Borrer. Frequent in Sussex : Mr. Jenner. 

 Cheshunt and neighbourhood : A. H. H. Oswestry : 

 Rev. T. Salwey. Ilfracombe; Swansea; Dolgelly and 

 Bangor, North Wales : Mr. Ralfs. 



A very distinct little species. The degree of constriction 

 of the neck varies considerably in different specimens ; and 

 this circumstance doubtless led to the institution on the part 

 of Ehrenberg of the Gomphonema capitatum, which is as- 

 suredly but a state of G. truncatum. 



3. GOMPHONEMA ACUMINATUM Ehr. 

 Plate XCIX. Fig. 1. 



Char. Frustules in front view cuneate and truncate. Lateral 

 surfaces constricted, acuminate, striated. 



G. minutum Ag., Conspect. Diatom. 1832, p. 34. ; Grev. 

 in Hook. Br. Flor. vol. ii. p. 410. Gomph. acuminatum, 

 Abhandl. der Akademie d. Wissensch. zu Berlin, 1831, 

 p. 86. ; Bericht. der Akademie d. Wissensch. zu Berlin, 

 1836, p. 53., 1837, p. 44.; Die Infusor. p. 217. t. xviii. 

 fig. 4. G. minutum Ralfs, in Annals, vol. xii. p. 462. 

 pi. xviii. f. 5. ; Jenner, in Flora of Tunbridge Wells, 

 p. 206. 



Hob. Sussex : Mr. Jenner. Cheshunt, &c. : A. H. H. 

 Barmouth : Rev. T. Salwey. Trengwainton ponds, 

 near Penzance, and pond on Towednack Moor, near St. 

 Ives ; Dolgelly : Mr. Ralfs. 



The degree of constriction and acumination of the frus- 

 tules would appear to be subject to very considerable variation. 

 As the species was published at nearly the same period, by 

 both Agardh and Ehrenberg, and apparently first by Ehren- 

 berg, I have retained the name of the latter which is infi- 

 nitely the more appropriate. 



