8 On the Diatomaceffi of the South of France and the Auvei-gne. 



Achnanthidium lineare, W. Sm. Valve linear, obtuse; strise ob- 

 scure. Length -0003" to -0007". v.v. 



Fresh water. Fountain of Yaucluse ; Lasswade near Edinburgh, 

 June 1854, Dr. Greville. 



Plate I. fig. 9. Achnanthidium lineare. 



Achnanthidium coarctatum, Breb. Valve liuear-elliptical, con- 

 stricted at the centre, attenuate, and constricted towards 

 the roimded extremities. Strife nioniliform, 24 in "OOl". 

 Length of frustule -0013" to -0018". v.v. 



Breb. in Kiitz. Sp. Alg. p. 54. ad specim. authen. quae dedit am. 

 De Brebisson. 



Fresh loater. Cave near Rovat ; Grassmere, Westmoreland, Aug. 

 1853, W. Sm. 



Plate T. fig. 10. Achnanthidium coarctatum. 



Amphitetras antediluviana, Ebr. 



Var. /3. Frustules cruciform, angles produced ; valves with a 

 deep sinus between each angle. 



Marine. Salt Pans near Agde, W. Sm. Stomach of Crab, Pro- 

 fessor Williamson, 1852. Near Ipswicli, Aug. 1852, Mr. Hodgson. 

 Poole Bay, Nov. 1849, W. Sm. NearCumbrae, Feb. 1854, Mr. R. 

 Hennedy. 



I had at first distributed the present variety as a distinct spe- 

 cies, and proposed to name it A. excavata, but the structure of 

 the valve is exactly that of the ordinary form ; and although the 

 produced angles and consequently concave valve, as well as the 

 deeply hollowed sides, give a very peculiar physiognomy to the 

 frustules, I am constrained to regard it as a variety of Ehren- 

 berg's well-known species. 



Plate I. fig. 11. Amphitetras antediluviana, var. i3. 



Orthosira spinosa, W. Sm. Filament fragile, often only par- 

 tially cohering; valves cylindrical, spinose at the line of 

 jvinction, striated ; strise moniliform, radiate, 30 in "001". 

 Breadth of filament -0005" to -0017". v.v. 



Fresh loater. Cave near Royat. Cave under Grand Cascade, 

 Mont Dore ; elevation 4236 feet. Braemar, Aug. 1854, l)r. Balfour. 



Plate I. fig. 12. Orthosira spinosa : a, filament cU-awn from a balsam 

 mounting ; and b, ditto from a dried specimen. 



It will be seen by the above lists, that only three of the spe- 

 cies collected during my late journey are to be regarded as 



