Mr. J. Ralfs on the British species of Gomphonema. 465 



unnoticed in our British works. Mr. Borrer, with his accustomed 

 kindness^ sent me several specimens from Henfield, some of them 

 recent and others gathered formerly, and also one gathered near 

 Yarmouth by Mr. Dawson Turner. On examining the latter, 

 which was less gelatinous than those from Henfield, I was sur- 

 prised to find that the frustules were attached to a stipes. Al- 

 though I could not detect this stipes in the dried specimens from 

 Henfield, I discovered it in the recent ones, and also in some fine 

 specimens sent me from Shrewsbury by Mr. Leighton. Shortly 

 afterwards I received from Mr. Berkeley recent specimens of 

 Greville's Gomph. Berkeleii, which proved to be the same plant. 

 Mr. Berkeley writes, that, as far as he can judge without seeing 

 an authentic specimen, he considers it to be the Echinella olivacea 

 of Lyngbye, t. 70, as it certainly is of Jurgens, Dec. xvi. no. 9. 



Mr. Berkeley has also afibrded me an opportunity of examining 

 Greville^s Gomph. minutissimum. In his specimen I find two spe- 

 cies mixed together; the more plentiful one has the frustules 

 similar to those described above, and indeed difi*ers from Gomph. 

 Berkeleii only in its scattered habit, and in the frustules being 

 attached more firmly to the stipes, which is more evident as the 

 plant does not form mucous masses. On these grounds, and as 

 I have since received from Mr. Hassall specimens of an interme- 

 diate character, I have been induced to consider it a variety of the 

 present species. The other species in Dr. Greville's specimen has 

 curved frustules, and as these are referred by Kutzing and Eh- 

 renberg to Gomph. minutissimum, I have described it below under 

 that name. 



On a front view the frustules of Gomph. Berkeleii most resem- 

 ble those of Gomph. pohliceforme, but the lateral aspect is very 

 different. The variety /3. especially approaches nearer to Gomph. 

 dichotomum ; the frustules however are shorter, broader and more 

 decidedly cuneate; the lateral surfaces also are broader, being 

 frequently as broad as the front. 



Plate XVIII. fig. 8. Gomphonema Berkeleii. 



7. G. minutissimum, Grev. Frustules cuneate, curved; terminal 

 puncta conspicuous, a stria from each extending the entire length 

 of the frustule; lateral surfaces clavate or lanceolate, striated. 

 Kutz. Syn. Diatom, p. 567. f. 43 ; Eh. Die Infus. p. 219. t. 18. 

 f. 5 ; Pritch. Infus. p. 228. Gomph. curvatum, Kutz. Syn. Diatom, 

 p. 567. f. 51 ; Kutz. Alg. aq. dulc. No. 76 ! 



/3. marinum. Stipes more branched, the striae running down the frus- 

 tule more strongly marked. 

 In slow streams, Shrewsbury, Mr. Leighton ; Shoreham, Kent, 



Mr. Jenner ; Cheshunt, Mr. Hassall ; near Dublin, Mr. Allman. 



Swansea. 



|S. On marine algse, Eastbourne, Sussex, Mr. Jenner, and Ireland, 



Mr. W. Thompson. Ilfracombe. 



