434 • DIATOMACE^. 



Synedra Ulna Ehr., Infus. p. 211. pi. xvii. fig. 1. ; 

 E. Ulna Jenner, in Flora of Tunbridge Wells, p. 204. 

 Hah. Common In ponds and ditches throughout Britain. 



An exceedingly distinct species, not likely to be con- 

 founded with any other. The extremities of the frustules 

 would appear to undergo the same change as has been ob- 

 served in those of Diatoma elongatum^ and to become 

 somewhat dilated. 



3. EXILAEIA FASCICULATA Kutz. 



Plate XCVII. Fig. 3. 



Char. Frustules small. In front view alternated at either 

 end ; in side view extremities acute. 



Exilaria Vaucheri(B, E. fasciculata, in part, Klitz., in 

 Linnasa, 1833, p. 560, 561. t. xv. p. 38. 40. Synedra 

 fasciculata ISihr., Infus. p. 212. t. xvii. fig. 2. Exilaria 

 truncata Harv., In Manual, p. 204. Diatoma truncatum 

 Grev., in Hook. Br. Fl. p. 407. 



Hah. Common in ditches, &c. 



Tills Is a very distinct little species : the frustules are often 

 in pairs, and owing to these being frequently but imperfectly 

 separated from each other, a curved or fan-shaped lamina is 

 produced. 



4. EXILAEIA LUNARIS. 



Plate XCVII. Fig. 4. 



Char. Frustules curved, small, slender, converging at the 

 extremities. 



Synedra lunaris Ehr., Die Infus. p. 212. pi. xvii. fig. 4. 

 Exilaria lunaria Jenner, in Flora of Tunbridge "Wells, 

 p. 204. 



A very distinct and pretty little species. 



