5i 



PYXIDICULA. 



B. Valves linear, rcniform, or cuneate. 



Valves cellular, similar to Coscinodiscus, but reniform .... Stoschia. 



f Valves elongated, linear or somewhat cuneate, with scattered puncta . Willemoesia. 



f Valves arcuate, at least on the dorsal side, and marked 

 with more or less scattered, often very coarse, puncta ; 

 girdle face straight .... Leudugeria. 



Valves not 

 reniform,' 



Valves 



arcuate or J 



linear, | 



cuneate. 



-rr , . f Valves cellular, furnished with a small 



Valves not 



arcuate : 



pseudo-nodule on the ventral margin . Euodia. 



^, ' ' Valves with radiating stripe, very delicate ; 

 ventral and dorsal margins usually fur- 

 ( cuneate. ^ n i s hed with small teeth ' . . Palmeria. 



Sect. I. Pyxide/e. - Valves inflated, convex, in the form 

 of a pyxidium or shaving box. 



GENUS 173. PYXIDICULA EHR, 1833. 



Fig, 258, Pyxidiada Mediterraneum. 



Fig. 259. P. [Dictyopyxis) brevis, 



Frustules with connecting zone very narrow. Valves convex, 

 disciform, or capuliform, without teeth or central spines, sometimes 

 with small marginal teeth. 



This genus, in which we include the genus Dictyopyxis of Ehrenberg, 

 consists of a few species which are specially differentiated from Stepha?wpyxis 

 (Meiosirece) by the absence of central teeth which unite the frustules to one 

 another. We give in the text P. Mediterraneum Grim. (fig. 258), and 

 Dictyopyxis brevis Grev. (fig. 259). 



