434 DIATOMACE^. 



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

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

 Hah. Common in ponds and ditches throughout Britain. 



yT^ l^ An exceedingly distinct species, not likely to be con- 

 ^^/p^omn{Q({ with any other. The extremities of the frustules 

 t)^x would appear to undergo the same change as has been ob- 

 served in those of Diatoma elongatum, and to become 

 somcAvhat dilated. 



3. EXILARIA FASCICULATA Kutz. 



Plate XCVII. Fig. 3. 



Char. Frustules small. In front view alternated at either 

 ' end ; in side view extremities acute. 



-jL Exilaria Vazicheriw, E. fasciculata, in part, Klitz., in 



Linn^ea, 1833, p. 560, 561. t. xv. p. 38. 40. Synedra 



fasciculata Ehr., 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. 



This 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. Exilaria lunaris. 



Plate XCVII. Fig. 4. 



Char. Frustules cui'ved, 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. 



