80 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Genus HEMIDISCUS Wallich 



Wallich's generic name in the Microscopical Journal for 1860 (p. 42) 

 antedates that of Bailey, Euodia (Pritchard, Inf., p. 852). It has the 

 incidental advantage of being far more descriptive that Euodia. 

 Cleve evidently prefers Hemidiscus for regarding " Euodia arcuata 

 sp. n" in Schroder's Phytoplankton Napelo he says it is Hemidiscus 

 cuneiformis. 



HEMIDISCUS CAPILLARIS Brun 



(Brun, Espec. Nouv., p. 26, pi. 17, fig. 4.) 



HEMIDISCUS CUNEIFORMIS Wallich 



(Micro. Journ., 1860, p. 42, pi. 2, figs. 3-4; H. L. Smith, Types, No. 161.) 



HEMIDISCUS HARDMANIANUS (H. L. Smith) Mann 



(H. L. Smith, Types, No. 287.) 



H. L. Smith places this diatom in Palmeria, Greville's perfectly 

 unnecessary genus. 



HEMIDISCUS INORNATUS Castracane 



(Castracane, Chall. Exp., p. 149, pi. 12, fig. 1.) 



. HEMIDISCUS JANISCHII Grunow 



See under Leudugeria. 



HEMIDISCUS RADIATUS (Castracane) Mann 



(Castracane, Chall. Exp., p. 150, pi. 12, fig. 4.) 



HEMIDISCUS VENTRICOSUS (Castracane) Mann 



(Castracane, Chall. Exp., p. 150, pi. 12, fig. 5.) 



HENSHAWIA, new genus 



Front (valve) view a narrow ellipse, its long axis three to six 

 times the length of the transverse one, the elliptical outline perfect 

 at the margin of the valve where it joins the girdle, but irregular on 

 the apparent upper plane of the valve, the valve being very deep or 

 convex, as shown in side (girdle) view; a deep groove extends up the 

 sides and across the middle of the valve, dividing it into two sym- 

 metrical halves, and in the center of this groove is a rosette of oval 

 beads, the outer ring close set and regular, the inner beads irregularly 

 arranged; the rest of the valve is covered with rows of oval beads, 

 punctate, and with an evident central dot, the rows being symmet- 

 rically and radially arranged, with reference to the central rosette; 

 in side (girdle) view the frustule is rectangular, each valve being as 

 deep as it is long, and the two valves being joined by a very broad 

 girdle; the length of the frustule, measured from the outer surfaces 

 of the valves, is therefore two to three times the length of the valves, 

 resembling in this respect some specimens of BiddulpMa pulchella 



