SPECIES OF DESMIDS. IOI 



^[ Lateral and basal lobes separated by a deep acute notch, 



Crux-MilitenstSy in 

 *[ Lateral and basal lobes separated by a shallow rounded notch, 



speciosa** 



/, Lobules deeply furcate; borders not serrate . . . dichotoma, in 

 /. not furcate, borders not serrate .... rtngens, 112 



/. " u borders serrate serrulata** 



i. End lobe remote from the lateral (n). 

 m. End lobe not remote from the lateral (o). 



n. End lobe triangular . . . ' triangularis, 115 



n. " not triangular . . hamata, 114 



o. Lobes closely approximate, radiating (/). 



o. < " " not radiating, end lobe truncate, 



truncata, 114 



p. End lobe triangular triangularis, 115 



/. " cuneate, end concave ....... conferta, 114 



/. very broad, end truncate or convex . . . crenata, 113 



r. Cytioderm papillose apiculata, no 



r. " not papillose (s). 



s. Basal lobes with 4 subdivisions, lateral with 8; apices of end lobe 



furcate rotata, fimbriata, 109 



s. " " " apices of end lobe 



not furcate cornuta. 



s. Basal lobes with 2 subdivisions, lateral with 4 (u). 

 s. Basal and lateral lobes with the same number of subdivision (v). 

 t. End lobe with i row of pearly granules .... Minnesotensis . \ 

 t. " without pearly granules (7). 



u. End lobe exserted on a long neck brachyptera, 1 10 



u. " exserted without long neck, its apices furcate, simplex, no 



v. Margins spinous brachyptera, no 



v. " not spinous bispinatd.\ 



y. Sinuses deep, inwardly widened and rounded; subdivisions of 



semi-cell 20-40; surface smooth radiosa, 109 



y. Sinuses deep, inwardly rounded, surface with rounded elevations, 



mamillata** 

 z. Lateral lobe deeply furcate, basal part perpendicular, furcations 



horizontal; ends bifid alata** 



aa. A row of centrally larger basal inflations across each semi-cell, 



verrucosa** 

 aa. No basal inflations; minutely granulate .... Jenneri, 115 



** F.-w Algae, p. 38 et seq. 



\ Journ. R. Micr. Soc., Dec. 1885. 



