BRITISH DIATOMACEjE. 43 



2. Grammatophora macilenta, n. sp. Frustules often curved ; 

 septa as in the last species ; valve linear, slightly inflated at centre 

 and extremities; stria? 60 in •001". Length of frustule •0011" to 

 •0056". Breadth of valve -00015". v.v. 



Marine. Salt Pans, Hampshire, Sept. 1854 ; Cork Harbour, July 1855, 

 W. Sm. (The Levant ; communicated by Mr. Johnson.) 



The F. V., like the valve, in this species, is always much narrower in pro- 

 portion to its length than in the last ; this arises from the less convexity of 

 the valves, and from the slight development of the connecting membrane. 

 The striae are also far more numerous than in G. marina ; and the frustule, 

 especially in the larger specimens, shows a decided tendency to assume a 

 curved form. 



Supp. Plate LXI. 382. 



3. Grammatophora serpentina, Kiitz. Septa with two or more 

 curvatures, and a hamulous extremity; valve linear, slightly attenu- 

 ate or cuneate towards the obtuse or rounded extremities ; striae 

 42 in -001". Length of frustule -0009" to -0062". Breadth of 

 valve -0007". v.v. 



Kiitz. Bacill. xxix. 82 ; Sp. Alg. p. 121. Striatella tceniceformis y, Ralfs, 

 Ann. vol. 11. pi. ix. 5. /3. 



Marine. Torbay, July 1846; Cork Harbour, Oct. 1855, &c, W. Sm. 

 Ilfracombe, March' 1852, Mr. Raffs. The Clyde, Feb. 1854, Mr. Hennedy. 

 (AlgoaBay; Guano fromlchaboe; Mediterranean near Marseilles, &c.,W. Sm.) 



Mr. West, while engraving the present species, called my attention to the 

 existence of a faint median line, with occasionally distinct central and terminal 

 nodules, in both G. marina and G. serpentina : he also remarks that the striae 

 in the former case are composed of markings in linear series ; while those of 

 G. serpentina have the striae made up of markings disposed in quincunx, the 

 resultant lines in the one being in consequence parallel, and in the other 

 oblique. There can be no doubt of the general accuracy of these remarks ; 

 but I have not been able to assure myself that these features are uniform and 

 constant, and therefore hesitate to adopt them as specific distinctions. 



4. Grammatophora ? Balfouriana, TV. Sm. Septa direct, without 

 curvatures, perforate ; valves linear, elliptical ; stria? 45 in *001". 

 Length of frustule -0005" to -0012". Breadth of valve -00015" to 

 •00025". v.s. 



Diatomella Balfouriana, Grev. Ann. ser. 2. vol. 15. pi. ix. 10-13. 



Fresh water. Canlochlan and Glen Callater, Perthshire, Aug. 1854, 



