BRITISH DESMIDIE^. 199 



4. Frond as broad as or broader than long 5 



Frond longer than broad 7 



5. Segments reniform ; end view with a slight lobe on each side 



at the middle Phaseolus. 



Segments elliptic in both front and end \'iews 6 



6. Empty frond reddish ; notches closed tinctum. 



Empty frond hyaline ; notches gaping bioculaium. 



7. Ends ronnded Cucnmis. 



Ends truncate 8 



8. Segments quadrate quadratiim. 



Segments oval with flattened ends pyramidatum. 



Segments truncato-triangular granatum. 



9. End view elliptic 10 



End view with a lobe at the middle of each side 19 



10. Frond smooth, crenate 11 



Frond rough with pearly granules which give a denticulate 



appearance to the margin 13 



1 1 . Sides and end of segments bicrenate Meneghinii. 



Segments with many crenatures 12 



1 2. Segments with flattened, minutely crenate ends ; spines of 



sporangium very short crenatum. 



Segments with romided, strongly crenate ends ; spines of spo- 

 rangium elongated undulatum. 



13. Segments truncato-triangular Botrytis. 



Segments not in the least triangular 14 



14. Frond elliptic ; granules large and confined to the margin ovale. 



Frond not elliptic ; granules not confined to the margin 15 



15. Frond twice as long as broad, with parallel sides amcenum. 



Frond not twice as long as broad ; sides not parallel 16 



16. Segments quadrangular conspersum. 



Segments rounded 17 



17. Pearly granules longer than broad Brebissonii. 



Pearly granules broader than long 18 



18. Granules giving a crenate appearance to the margin . . tetraophthalmum. 

 Granules giving a denticulate appearance to the margin, margaritiferum. 



19. Segments bordered by papillse-like granules ; end view with 



truncate ends cristatum. 



Pearly granules neither papillse-like nor confined to the mar- 

 gin ; end view with rounded ends 20 



20. Segments bordered with denticulated crenatures ccelatum. 



Segments not crenate 21 



