8 On the Diatomacese of the South of France and the Auvergne. 



Achnanthidium linear e, AV. Sm. Valve linear, obtuse ; strise ob- 

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



Fresh water. Fountain of Vaucluse ; Lassvvade near Edinburgh, 

 June 1854, Dr. Greville. 



Plate I. fig. 9. Achnanthidium lineare. 



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

 stricted at the centre, attenuate, and constricted towards 

 the rounded extremities. Strise moniliform, 24 in '001". 

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



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

 De Brebisson. 



Fresh ivater. Cave near Royat ; Grassmere, Westmoreland, Aug. 

 1853, TF. Sm. 



Plate T. fig. 10. Achnanthidium coarctatum. 



Amphitetras antediluvianaj Ehr. 



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

 deep sinus between each angle. 



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

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

 Poole Bay, Nov. 1849, ?F. 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. /3. 



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

 tially cohering; valves cylindrical, spinose at the line of 

 junction, striated ; strise moniliform, radiate, 30 in 'OOl". 

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



Fresh water. Cave near Royat. Cave imder Grand Cascade, 

 Mont Dore ; elevation 4236 feet. Braemar, Aug. 1854, Br. Balfour. 



Plate I. fig. 12. Orthosira spinosa : a, filament drawn 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 



