BRITISH DIATOMACE^. 59 



24. Pinnularia interrupta, W. Sm. V. linear, constricted at the 

 rounded extremities ; costae absent from the centre of the valve, 

 contiguous, 24 in -001". Length -0012" to -0022". v.v. 



Stauroneis parva, Kiitz. Bacill. xxix. 23. Sp. Alg. p. 92. specim. misit cl. 

 De Brebisson. 



Fresh water. With the last, and probably only a variety of the same. 

 Plate XIX. 184. 



Genus 21. STAURONEIS, Ehr. 



Frustules free, oblong or lanceolate ; valves convex ; striated, vi^ith a 

 median line and terminal nodules; central nodule dilated into a 

 band (Stauros) free from striae. 



1 . Stauroneis Phoenicenteron, Ehr. V. lanceolate, obtuse ; stauros 

 linear, reaching the margin ; striae 33 in '001". Length '0055" to 

 •00G6". v.v. 



Kiitz. Bacill. iii. 53. Navicula Phcenicenteron, Ehr. Inf. xiii. 1. Prit. Anim. 

 iii. 139. XV. 17 & 18. 



Freshwater: very common. Wareham, Sept, 1847; Lewes, Aug. 1850; 

 Jersey, Aug. 1852, W. Sm. Lough Mourne and Peterhead Deposits. Prem- 

 nay Peat. Cantyre Peat. (North America.) 



Plate XIX. 185. 



2. Stauroneis gracilis, Ehr. V. lanceolate, obtuse ; stauros linear, 

 scarcely reaching the margin ; striae very delicate, 45 in 'OOl". 

 Length -0028" to -0036". v.v. 



Ehr. m Kiitz. Bacill. xxix. 3 ? 



Fresh water. Bindon Abbey, Dorsetshire, May 1849, TF. Sm. Wray 

 near Lancaster, Oct. 1852, Mr. G. Smith. Dolgelly Earth. Lough Mourne 

 Deposit. Cantyre Peat. (Little Falls, New York, and Nova Scotia.) 



Plate XIX. 186. 



3. Stauroneis acuta, n. sp. F. V. oblong; V. lanceolate, acute, 

 inflected at the extremities ; stauros dilated towards the margin of 

 valve; striae 30 in -001". Length -0033" to -0057". v.v. 



"A species oi Navicula,'" Quek. II. C. xii. 26. 



