SCENEDE8MUS. 393 



Leibleini Ktitz., Synops. Desmid. in Linnaea, 1833, 

 p. 607. fig. 98. ; Menegh., 1. c. p. 207. Scenedesmus 

 bijugatus, trijugatus, and minor Ktitz., 1. c. p. 607. figs. 

 97. 99. ; Jenner, 1. c. p. 200. 



Hob. Storrington Common and Eastbourn, Sussex ; 

 Shoreham, Kent : Mr. Jenner. Cheshunt : A. H. H. 

 Dolgelly: Mr. Ralfs. p. Dolgelly : Mr. Ealfs. 

 7. Weston Bogs, near Southampton : Mr. Jenner. 

 Bristol : Mr. Thwaites. Dolgelly, and Penzance : Mr. 

 Rolfs. 



The cells in this species are quadrangular, about three 

 times as long as broad, and rounded slightly at their ex- 

 tremities ; the external ones are usually more turgid, and the 

 bristles at their extremities are directed outwards. The 

 variety ft and 7 are figured by Ehrenberg. 



2. SCENEDESMUS DIMORPHUS Kutz. 

 Plate XCII. Fig. 13. 



Char. Cells from four to eight in each frond, arranged in a 

 single series. Inner cells fusiform, attenuated at each 

 end; outer externally lunate. 



Achmanthis dimorpha and bilunulata Turpin, Mem. du 

 Mus. xvi. p. 309. pl.xiii. f. 11, 12, 1828. Scenedesmus 

 pectinatus Meyen, Nov. Act. Nat. Cur. xiv. p. 375. 

 tab. 43. f. 34. 1829. Scenedesmus bilunulatus, dimorphus, 

 pectinatus Kiitz., Synops. Diat. Linnaea, 1833. 608. 

 t. xix. fig. 93. ; Ehr. Die Infus. p. 150. tab. x. fig. 17. ; 

 Ralfs, in Annals, p. 403. pi. xii. fig. 5. 



Hob. Dolgelly : Mr. Rolfs. Near Bristol : Mr. Thwaites. 



This is a very distinct and pretty species. 



3. SCENEDESMUS ACUTUS Meyen. 



Plate XCII. Fig. 14. 

 Char. ec Cells two to six, fusiform, acute at both ends, un- 



