MANN DIATOMS OF THE ALBATROSS VOYAi _'.*'>.", 



True raphe generally evident; valve generally not keeled; if keeled, the raphe 

 coincident with keel I Nitzschia N w u i loidi 



a. Valve with evidenl raphe; keel generally absent, or win mi present . without 

 beading; markings generally pinnate. (Navicul] 



a. Frustule aot wedge-shaped in either zonal 01 \ alval view; vah e straight 



or sigmoid; uever crescent-shaped Navtculinae 



Frustule without internal compartment* along the margine of the 

 \ al 

 Valve without keel \ \ . i< i lidae 



Raphe straight or barely undulate, its tips turned toward 

 the same side of the valve; outline of valve boat-shaped. 



I X.\ Yl< I I 



Halves of the raphe Dot Burrounded by an ele 

 parallel ridge; both ends of each half terminating in 

 a rounded or elongated bead; central and terminal 

 nodules of valve round <>r broadened transversely. 



\<n icula p. 3 

 Halves of raphe surrounded by an elevated parallel 

 ridge, the ends not terminating in beads, or rarely the 

 outer end of each balf terminating in a round bead; 

 centra] nodule greatly narrowed laterally and pro- 

 longed longitudinally, thereby separating the two 

 halves of the raphe by a ridged space of from one- 

 sixth to fully two-thirds the length of the valve. 



F ustulia p 

 Raphe strongly curved into an S. rarely into a C; sides ' 

 valve usually corresponding to the same curve; marking 

 uniform over entire valve, of fine, closely set lines, 

 arranged either in two series, one transverse and one lon- 

 gitudinal, or in three series, one transverse and the other 

 two at angles of 60 c to each other; tips of the raphe 

 turned to opposite sides of the valve. Gyrosigm \ 1. 



osigma p 

 Valve with keel. (Amphiproridae. 



Raphe s1 raight . n< >1 median Plagiotro\ 



Raphe sigmoid, median imphipro 



Frustule with internal compartments along the margin of the valve. 

 Characters, except the lateral compartments, the same as in 

 Naviculae. Mastogloiae Mastogloia p. 3 - 



b. Frustule wedge-shaped in both the zonal and valval view; valve 



straight. Gomphoneminae Gomphonema p. 370). 



c. Frustule wedge-shaped, as to its transverse axis, that is, the t\\.> 



valves approaching nearer on one Bide than on the other; valve 

 in<»re or Less crescent-shaped. Coi i onemin \ i 

 Valve without transverse ribs; raphe evident. 



Valve nol strongly asymmetrical; the raphe nearer the median 

 line than the concave side of the valve; /.one narrow, hya- 

 line ' p. 371 



Valve strongly asymmetrical, the raphe much nearer the con- 

 cave Bide of the valve than the median line; zone wide, com- 

 posed of em \ era! bands, beaded toi 



Valve with transverse ribs; raphe obscure or represented by a form 

 of peeudoraphe consisting of a continuous bow-shaped rid| 



Cy8toph 



