BRITISH DIATOMACE^. 29 



2. Campylodiscus costatus, TV. Sm. V. circular ; canaliculi from 

 30 to 40, in length about half of the radius ; centre of V. minutely 

 punctate. Diam. -0025" to -0050". v.v. 



Var. /3. V. somewhat elliptical, disc distinctly punctate. 



W. Sm. Ann. 2nd Ser. vol. vii. pi. i. 1. Bright. Inf. pi. ix. 10. 



Fresh water. River Frome near Dorchester, May 1849. Near Lewes, 

 Aug. 1850, W. Sm. Bramley Spring near Guildford, Mr. Capron. Norfolk, 

 Mr. Brightwell. Lough Mourne Deposit. Peterhead Deposit. Dolgelly 

 Earth, &c. &c. Var. /?. Cantyre Peat. 



Plate VI. 52. Var. /3. PI. VII. 52. 



3. Campylodiscus Hodgsonii, n. sp. V. nearly circular ; canaliculi 

 very numerous, 100 or upwards, in length about one-third of the 

 radius ; centre of the disc cellular ; cells circular, in radiating lines. 

 Diam. -0018" to -0052". v.s. 



Marine. Near Ipswich, Mr. Hodgson, July 1851. Poole Bay, Oct. 1851, 

 W. Sm. 



This beautiful species varies much in size, but presents throughout its cha- 

 racteristic features. The disc is frequently traversed by a smooth line cor- 

 responding with its longest diameter : a F. V. shows us that this line is formed 

 by a ridge and two contiguous furrows passing across the valve. It is worthy 

 of remark that the ridges on the two valves of the same frustule are not 

 uniformly opposite, but cross each other at various angles : a similar circum- 

 stance may sometimes be noted in Eupodiscus and other disciform frustules. 



Plate VI. 6*. .' ' 



4. Campylodiscus spiralis, W. Sm. F. tvi^isted so as to present a 

 spiral outline; V. elliptical; canaliculi about 60, nearly parallel; centre 

 of the disc minutely punctate. Longest diam. "0042" to '0083". v.v. 



W. Sm. Ann. 2nd Ser. vol. vii. pi. i. 2, Surirella spiralis, Kiitz. Bacill. iii. 64? 



Freshwater. Bramley near Gvdldford, Oct. XSAS, Mr. Capron. Lanshaw 

 Spa, near Katefield, Lancashire, Jan. 1852, Mr. Geo. Smith. Norfolk, Mr. 

 Brightwell. 



Plate VII. 54. Frustule with endochrome. Frontispiece, fig. LIV. 



5. Campylodiscus cribrosus, W. Sm. V. nearly circular ; disc cel- 

 lular ; cells irregularly circular, in radiating lines. Diam. '0041" to 

 •0052". v.v. 



