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^ 1 



MANN DIATOMS OF THE ALBATROSS VOYAGES. 235 



C. True raplie generally evident; valve generally not keeled; if keeled, tin* raphe 

 coincident with keel (Nit/^schia). (Xaviculoideae.) 



a. Valve with evident raphe; kiH'l gi^nt^rallyabi^ent, or wiuMi present, ^^ ilhout 

 beading; markings generally pinnate. (Naviculeae.) 

 (L Frustulenot wedge-shap(vl \n ciUicr zonal or valval view; valveytraiglit 

 or yiginoid; never ere^scent-^sliaped. (Naviculinak.) 



Frustnle without iiiLc^rinil coinpartments along the nuugiiusof the 

 valves. 

 Valve without keel. (Xavtoulidap:.) 



Rai>he straight or barely undnlat<\ its tip?? turtied toward 

 the same si<h' nf I ho valve; nutline of valve boat-shaped. 

 (Navuii.ae.) 



Halvosof tho raplu' not snrrounded by an <devaled 

 parallel ridgi"; Itolh ends of earh half IrrniiinU ing in 

 a rounded or elniigated bead; central and terminal 

 nodules <»f valve round or broadened transv(^rsely. 



Narinda fp. 3:53). 

 Halves of raphe surrounded by an eluvattnl paralM 

 ridge, the ends not terminating in bea<ls, or ran'ly tlu> 

 outer end of each ludf terminal ing in a round bead; 

 central nochile greatly narrowM^d lab-rally and pro- 

 longed longitudinally, therel)y separating the two 

 halves of tlu^ rajdii^ by a ridged space (jf from one- 

 sixth to fulh hvo-thirds tlu^ lenti:tli i>f the valve. 



FrustuUa i p. 359 l 

 Raphe strongly rnrvinl inlo an S. imc^y into a C; sicb's of 

 valve usually rurr(^s])onding In the same curve; marking 

 nnifonn over (^itire valve, of tine, closely set lines, 

 arranged eithcT- iu l\vn sc^ries, one transvi'rse and one lon- 

 gitudinal, 01' in thre(^ series, one transverse and the other 

 two at angles i)i (]()° to (*ach other; tips of the raphe 

 turned to opixtsiie sides of tlu' valvt*. (Gyk(>.su;m a e.) 



-i 



ni/rosi(ji){ti (p. :M\2), 

 Valve with kcn'l. (Ami-uipkoimoak.) 



Ra])he straigliU ntit median Plaglolropls {y). M7). 



Raphe signidid, lui'dian Am pJnprora {p. 3#>8). 



Frustnle with internal <'nin]>artnients along ilie margin of the valve. 



Characters, except tin* later^d (^impavtments. ihe sanu^ as in 



Naviculae. (MAsroiiLoiA k) Xfastogloia (p, 368). 



b. Frustnle wedge-shaped in bntli iht^ zonal and valval view; valve 



straight. (GoMriu)XEMi\AE) Oompltonana (p, 370). 



c. FrustiUe wedge-shaped as to its transverse axis, that is, the two 



valves approaching nearer on one side than uu the otlu^r; valve 



more or less crescent-shaped. (Coccoxeminae.) 



Valve wdthout transverse ribs; raphe evident. 



Valve not strongly asymmetrical; the raphe nearer the median 

 line llian the coTu^ave side of the valve; Z(me narrow, hya- 

 line Covconevia (p. 371). 



Valv(^ strongly asyinmetricab th<' raphe much nt^arer tlu^ con- 

 cave side cjf tlie valve than the me<lian line; zone wid(\ com- 

 posed of several bands, beaded Amphora (p. 373b 



Valve witli transverse ril)s; i"a[)he (jbscure or rei>resenti'd by a form 



of peeudoraphe consisting of a eontinuous bow-shaped i'i<lge. 



Cy^laph ura i\}. 377). 



