6 Prof. W. Smith on the Diatomacese of the 



Br. Gregory. Braemar, Aug. 1854, Dr. Balfour. Var. y. Spring 

 at Chateau Vert near Marseilles. Braemar, Aug. 1854, Dr. Balfour. 



Plate I. fig. 2 /3. Gornphonema capitatum, var. /3. Fig. 2 y. G. capi- 

 tatum, var. y. 



Gornphonema Brebissonii, Kiitz. Valve constricted ahove the 

 centre, upper extremity cuneate, obtuse, lower gradually 

 attenuated and acute. 'Strire 24 in -001". Length -0013" 

 to -0018". v.v. 



Kiitz. in Sp. Alg. p. ^&. ad specim. authen. quae dedit am. De Brif- 

 bisson. 



Fresh water. Puy du Cliergue. 



But slightly differing from G. acvminatuvi, var. 7, W. Sm. 

 Syn. Brit. Diat. pi. 28. 238. a'" ; and probably only another va- 

 riety of the same species. 



Plate I. fig. 3. Gornphonema Brebissonii. 



Gornphonema elongatum, W. Sm. Valves inflated at centre, 

 afterwards constricted towards both extremities, the upper 

 of which is capitate, or somewhat cuneate, the lower slightly 

 inflated below the constriction, afterwards attenuated and 

 obtuse. Sti-ise 24 in -001". Length -0018" to -0045". v.v. 



Gornphonema Brebissonii, Greg, in Mic. Journ. vol. ii. p. 99. pi. 4.18. 

 Fresh ivater. Puy du Cliergue, JF. Sm. Mull Deposit, Dr. Gre- 

 gorxj. Wisbeach, April 1854, Mr. G. Smith. 



This may probably be a vanety of G. Brebissonii, Kiitz., with 

 which it occurs intermixed iu the French gathering; both are 

 in my opinion closely allied to G. acuminatum. 



Plate I. fig. 4. Gornphonema elongatum. 



Diatoma vulgare, Bory. 



Var. 0. Valve linear, extremities gradually and slightly at- 

 tenuated. Length of frustulc -0018" to -0030". v.v. 



Diatoma fenue, Ag., ad specim. in herb. Grev. 



Fresh water. Fountain in court of the Hotel des Colonies, Mar- 

 seilles ; Canal du Midi, and Canal de Crapone ; Plumpton, Sussex, 

 April 1852, JF. Sm. Pentland Hills, April 1821, Dr. Greville. 



The valve in the normal form of D. vuUjare is elliptical and 

 suddenly attenuated towards the extremities. 

 Plate I. fig. 5. Diatoma vulgare, var. /3. 



Diatoma grande, W^ Sm. Valve linear, constricted near the 

 capitate and rounded extremities. Costre 24 in -001". 



