10 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



On another point of nomenclature this report is in accord with Van 

 Heurck, as to P. T. Cleve's plan for dividing the unwieldy genus 

 Navicula into a number of genera. He accepts these as useful sub- 

 generic divisions of that huge genus, but considers them to be too 

 difficult of sharp definition to justify their adoption as valid genera. 

 But he does recognize, and I think correctly, three exceptions to the 

 foregoing, Cistula, Cymatoneis , and Frustulia. For the last he favors 

 Brebisson's synonym, Van Heurckia, but with this I can not agree- 

 As will be explained under these names, these three seem to be suffi- 

 ciently unlike other Naviculae to justify their separation. 



The general custom among diatomists of capitalizing proper names 

 is not followed in this report, as it conflicts with the rules governing 

 the scientific publications issued by the United States National 

 Museum. The author therefore contents himself with here stating 

 that to him the necessity for such capitalization seems to be at times 

 undeniable; as, for example, Navicula Liber W. Smith. 



All of the material examined for this report was collected by the 

 steamer Albatross of the United States Bureau of Fisheries; and the 

 writer wishes to express here his appreciation of the great service the 

 Bureau of Fisheries has rendered to science, and especially to ocean- 

 ography, by these and the vast number of other collections it has 

 secured and freely made available to investigators. 



As the genera and their species are both arranged in the text in 

 strict alphabetical order, a final alphabetical index is omitted as 

 unnecessary. 



GENERA AND SPECIES, WITH SYSTEMATIC DISCUSSIONS 

 Genus ACHNANTHES Bory 



ACHNANTHES COCCONEIFORMIS, new species 



Plate 1, fig. 1 



Valves broadly elliptical with a barely perceptible angular or pris- 

 matic outline; apices pointed; under valve marked with strong, smooth 

 costae slightly radial and straight at the center of the valve, increas- 

 ingly radial and curved toward the apices; each costa enlarged at the 

 outer marginal end; a narrow stauros reaching to the margin; central 

 area narrow, el'iptical, about one-fifth the width of the valve, reach- 

 ing the apices. The valve figured in Schmidt's Atlas, plate 1 98, figure 

 41, unnamed, seems to be the same diatom. 



Length 0.079; width 0.033; costae G in 0.01 mm. 



Type.— Cat. No. 43560, U.S.N. M. 



ACHNANTHES COMPACTA, new species 



Plate 1, fig. 2 



Valves elongated, with evenly rounded ends and parallel sides barely 

 constricted at the center; under valve crossed by double rows of 

 beading separated by costae, as in A. longipes Agardh, nearly trans- 



