SCENEDESMU9. 393 



Leihleini Kiitz., Synops. Desmid. in Linnoea, 1833, 

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

 hijugatus, trijugatus, and minor Kiitz., 1. c. p. 607. figs. 

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

 Hah. Storrington Common and Eastbourn, Sussex ; 

 Shoreham, Kent : Mr. Jenner. Chesbnnt : A. 11. H. 

 Dolgclly: Mr. Bolfs. — ^. Dolgelly : Mr. Balfs. — 

 y. Weston Bogs, near Southampton : 31?'. Jenner. 

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

 Rolfs. 



The cells in this species are quadrangular, alDOut 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 /3 and 7 are figured by Ehrenherg. 



2. SCENEDESMUS DIMORPHUS Kiitz. 



Plate XCII. Fig. 13. 



Char. Cells fro7n four to eight in each frond, arranged in a 

 single series. Inner cells fusiform, attenuated at each 

 end ; outer externally lunate. 



Achmanthis dimorjiha and bilunulata Turpin, IMcm. du 

 Mus. xvi. p. 309. pi. xiii. f. 1 1, 12, 1828. Scenedcsmus 

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

 tab. 43. f. 34. 1829. Scenedcsmus bilumdatus, dimorphtts, 

 pectinatus Kiitz., Synops. Diat. Liuna3a, 1833. 608. 

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

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



Ilah. Dolgelly : Mr. Ealfs. Near Bristol : Mr. Thwaitcs. 



This is a very distinct and pretty species. 



3. SCENEDESMUS ACUTUS MegeU. 



Plate XCII. Fig. 14. 

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



