BRITISH DIATOMACEJ:. 13 



3. Himantidium Soleirolii, Kiitz. V. linear, arcuate, extremities 

 rounded; striae 30 in -001". Length of F. -0005" to -0042". 

 Breadth of V. -0003". v.v. 



Kiitz. Bacill. xvi. 9. ad specim. authen. quae dedit. cl. De Brebisson. Raben. 

 Siissw. Diat. 1 . 3. Fragilariapectinalis, var., Ralfs, Ann. vol. xii. pi. ii. 3. 

 Hass. Alg. xcv. 3. 



Fresh water. "Wareham, Dorsetshire, Mar. 1848, W. Sm. In Scotland, 

 communicated by Mr. R. Beck. Tunbridge Wells, Dec. 1842, Mr.Jenner. 

 (Falaise, M. Be Brebisson.) 



This species so frequently occurs with internal cells, forming a variety 

 similar to the one noted in Meridion, that Professor Kiitzing has included 

 this peculiarity in his specific description. There is no doubt, however, of its 

 being merely an accidental modification of cell-growth, as we frequently find 

 in the same filament cells thus formed, and others following the normal mode 

 of self-division. 



Plate XXXIII. 282. and PL XXXV. 282/'. 



Sect. II. Frustules rarely united into a filament. 



4. Himantidium Arcus, W. Sm. F. V. frequently arcuate ; valve 

 arcuate, linear, or with dorsum slightly elevated, constricted towards 

 the rounded extremities. Striae 42 in "001". Length of frustule 



0012" to -0024". v.v. 



Kiitz. Bacill. xxix. 43. ad specim. authen. quae dedit cl. De Brebisson. 

 Raben. Siissw. Diat. 1.6. Eunotia Arcus, Ehr. Inf. xxi. 22 1 Fragilaria 

 pectinalis, inconj. Thw. Ann. vol. 20. xxii. A. 



Fresh water. Wareham, Sept. 1848 and Sept. 1851. Rackham, Sussex, 

 Aug. 1853, W. Sm. Dolgelly Earth, Peterhead and Mull Deposits. 



Plate XXXIII. 283. Suppl. PI. LX. 283. 



5. Himantidium bidens, Ehr. Valve arcuate, dorsum with two 

 elevations constricted towards the truncate extremities. Striae 27 

 in -001". Length of frustule -0024" to -0031". Breadth of V. 

 •0007". v.s. 



Kiitz. Sp. Alg. p. 9. Eunotia bigibba, Kiitz. Sp. Alg. p. 6 ? Greg. M. J. 

 vol. 2. iv. 3. 



Fresh water. Lough Island Reavey Deposit. Dolgelly Earth. Mull 

 Deposit. 



Plate XXXIII. 284. 



