60 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



20 of these septa, thus dividing the valve into 20 or more rectilinear 

 compartments. 



Length, 0.414; width, 0.028 mm. 



A minute and fragile species that possibly is a sickle-shaped variety 

 of 0. elongata Bailey (New Species and Localities, p. 8, pi. 1 figs. 10- 

 11), especially as Bailey notes the dimness of the crosslines at the 

 center of the valve, mentioned above. But Bailey's form is more 

 like 0. moniligera Ehrenberg than like this Philippine form, not only 

 in being straight, but in the cross septa ("vittae") and the more 

 sudden increase in the width of the valve above the long narrow basal 

 part. The fact is, it may be found eventually that both these are 

 merely varietal modifications of C. moniligera. Indeed the unique 

 characters of the genus hint at its being monotypic. 



Type.— Cat. No. 43607, U.S.N.M. 



Genus COCCONEIS (Ehrenberg) Grunow 



COCCONEIS APICULATA A. Schmidt 



(Schmidt, Atlas, pi. 198, fig. 31, and pi. 198, fig. 38, no name.) 



I find the figure above with no name to be the same as Schmidt's 

 Atlas, plate 198, figure 31. It may also be synonymous with "Rhaph- 

 oneis mammalis Cast.," Report of the Challenger Expedition, plate 

 26, figure 3, but this is uncertain. Were the two the same Castracane's 

 name would stand, being given in 1886 and Schmidt's in 1895. 



See a discussion of these forms under C. citronella, new species. 



COCCONEIS CIRCULIFERA, new species 



Plate 13, fig. 2 



Valve oval, with sharp but not produced apices; markings of closely 

 set lines indistinctly beaded, slightly undulating in unison, so that 

 false longitudinal shadow lines parallel with the margin appear by 

 change of optical focus; a narrow spindle-shaped hyaline area hardly 

 reaching to the apices; on one side, adjacent to this hyaline area, not 

 to the margin of the valve, is a small ring joined to a lunate half 

 ring on its inner side, easily mistaken for two rings, one showing 

 through from under the valve and slightly out of center with the 

 upper first ring, whereas this ring and adjacent semiring are repro- 

 duced on each valve. Margin of valve heavy and hyaline. 



Length, 0.056; width, 0.036; lines at margin, 11 in 0.01 mm. 



Although there is a similarity between this and Achnanihes hetero- 

 morpha Grunow, as figured in Schmidt's Atlas, plate 198, figures 

 52-58, the difference in the markings, especially the position of the 

 ocellus and its peculiar double form in this species, would preclude 

 their being united, even if the side (girdle) view did not reveal the 

 absence of any bend across tiie middle of the frustule, such as belongs 

 to members of the genus Achnanihes. 



Type.— Cat. No. 43608, U.S.N.M. 



