62 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



A. Schmidt and illustrates in the latter's Atlas, plate 198, figures 31-32. 

 A further addition to the Cleve muddle, but for which he was less 

 responsible, is his adding to the above Stauroneis obesa Greville, as 

 given in Greville's Diatoms from the South Pacific, page 237, plate 

 3, figure 12. In fact the under valve of C. citronella Mann and S. 

 obesa Greville are so remarkably alike at first sight that Cleve would 

 have needed to compare actual specimens of the two to realize their 

 difference. I have accordingly here illustrated the true S. obesa, re- 

 named Navicula obesa (Greville) Mann, and also a variety of it, for 

 the purpose of comparison. It will be seen that the lines of beading 

 of N. obesa are much coarser than in C. citronella and differently 

 arranged at the center of the valve. The measurements of the lines 

 are, C. citronella 21-25 in 0.01 mm., and N. obesa 9.2-9.4 in 0.01 

 mm., the two diatoms being almost the same size. But what settles 

 the matter is that in N. obesa both valves are exactly alike and both 

 have rhaphes. The specimen here figured is a complete frustule 

 and shows this fact plainly. Doubtless Greville saw this and was 

 certain of the Navicula (Stauroneis) character of his specimen, a con- 

 cession to that able diatomist that Cleve failed to make. It may be 

 here added that Castracane's u RJiapJioneis mammalis" is probably 

 a synonym of Cocconeis robustus Leuduger-Fortmorel in Diatoms of 

 Ceylan, plate 1, figure 1, and that the unnamed figure in Schmidt's 

 Atlas, plate 198, figure 41, is a phase of the same diatom. 

 Type.— Cat. No. 43609, U.S.N. M. 



COCCONEIS COMPOSITA A. Schmidt 



(Schmidt, Atlas, pi. 196, figs. 4-5.) 



This is rather close to C. Jieteroidea Hantzsch and could be so clas 

 sified as a well-marked variety. 



COCCONEIS CUBVIROTUNDA Tempore and Brun 



(Brun, Diat. Jap., p. 32, pi. 8, fig. 6; Schmidt, Atlas, pi. 195, figs. 12-16.) 



This also is close to C. Jieteroidea Hantzsch; De Toni (Syl. Alg., 

 p. 456) considers it to be intermediate between C. Jieteroidea and 

 C. pellucida Grunow. 



COCCONEIS CYCLOPHORA Grunow 



(Van Heurck, Synopsis, pi. 30, figs. 24-25; Schmidt, Atlas, pi. 197, figs. 20, 

 26, 30.) 



COCCONEIS DISTANS Gregory 



(Gregory, Glenshira, Diat,, pi. 4, fig. 9; Diat,, Clyde, pi. 1, fig. 23; H. L. Smith, 

 Types, No. 70.) 



An enormous number of species has been grouped by De Toni 

 and others under the very variable C. scutellum Ehrenberg, of which 

 this is one. Without passing judgment on the others, I am sure this 

 species can not be so disposed of without rendering more difficult its 



