CONSPECTUS OF TIIK K.UI I LI KS AM) ( i K\ KRA. 



TKIHK III. 



either 



FRUSTULES 

 generally cir- 

 cular, s ub -cir- 

 cular or angnlai 1 

 in s. v., more 

 rarely eliptical 

 oval, or bacil- 

 lar. 



; 



never 



CRYPTO RAPHIDIE^E. 



much developed in f. v., 

 ami filamentous ; or 



with processes, t eet h. 

 s])incs. or uwiis ; or 



more 01- less hyaline or 

 irregular ; or 



transversely septate (or 

 cost ate) in f. v. 



with a central liiirttr 

 blank space or true 

 raphe, on the valves, 

 except a raphe or 

 pse ado - rap he in K' : i 

 phidodiscus. 



v. microscope, "May, 



1889, p. i:;r>. 



I 



ANALYSIS <)F THE FAMILIES. 



TRIBE I. RAPHIDIE.K. 



Lettered figures refer to Families named in last paragraph of each section. 

 Plain tiyures refer to the corresponding numbers on the left of each section. 



I" Frustules with valves alike 2 



( Frustules with valves unlike 1 



-. ( Valves cuneate *< ' 



( Valves not cuneate 7 



., \ Valves symmetrically divided by the raphe . 4 



( Valves not so divided 



i Valves alate, or obliquely striate 4 



.'!. Valves not as above, more or less arcuate or cymlti- 



( form 



\ Valves with central nodule equally distant from ends. 



( Valves not as above 5 



_ < Valves with central nodule obscure or wanting.. M5 



( Valves not as above ' 



i Valves with central nodule unequally distant from 

 (>. ends 8( A 



( Valves not as above 7 



f Frustules gen aflexed, nodule or stauros on one valve, 

 usually on the concave margin i at the constric- 

 tion , valves rarely broadly oval . 



I All others, valves generally broadly oval, rarely l>ent SK 



9 



