112 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



this and the unnamed specimens figured in Schmidt's Atlas, plate 198, 

 figures 35, 36, and 40, because he failed to consider that Greville 

 might have been dealing with an unquestionable Navicula (" Stauro- 

 neis") proven by both valves being identical in markings and both 

 having rhaphes. By means of such specimens I have been able to 

 reestablish the validity of Greville's classification, and I include two 

 photographs for comparison with that of the under valve of 0. citron- 

 ella. It will be seen that the identity claimed by Cleve is deceptive, 

 because both in form and in the pattern and coarseness of the beading 

 there are easily overlooked but genuine differences. Thus Greville's 

 type form gives 8.5 to 9.5 lines in 0.01 mm., my typical specimen 

 9.4 and my varietal specimen 9.2 lines in 0.01 mm., while Cleve says 

 that the corresponding valves in his combination give 21 to 25 lines 

 in 0.01 mm. The arrangement of the lines is also different, as is 

 especially evident about the center of the valve and adjacent to the 

 small stauros. 



NAVICULA OCELLATA. new species 



Plate 24, fig. 2 



Valve an accurate oval, crossed by fine, closely set unbeaded lines, 

 leaving a lenticular median area about one-quarter the width of the 

 valve, which gradually narrows to a mere thread at the apices; a row 

 of similiar but very short beaded lines on either side of the rhaphe 

 somewhat flared outward at their beginning near the center, and 

 stopping somewhat short of the apices, to which the raphe continues; 

 rhaphe line depressed; a large central nodule; the inner ends of the 

 rhaphe bent right and left above and below it ; on either side of the 

 center the crosslines are interrupted by two indentical large ovate 

 hyaline areas or ocellae ; occasionally one of these is more obscure than 

 the other, though not wanting entirely; rim stout and hyaline; cross- 

 lines transverse only at the middle, progressively curved outward as 

 they approach the apices. 



Length, 0.062-0:082; width, 0.026-0.037; 11 to 14 lines in 0.01 mm- 



A slight resemblance to this species is found in the rather ques- 

 tionable figure of " Stauroneis robusta " Petit, as given in Peragallo's 

 Diatomees, France, plate 29, figure 9, the original figure being in Petit 

 Journal of Royal Microscopical Society, 1878, plate 15, figure 16. 



Type.— Cat. No. 43652, U.S.N.M. 



NAVICULA OPHIOCEPHALA Cleve and Grove 



(Le Diat., vol. 1, p. 57, pi. 9 fig. 13; Schmidt, Atlas, pi. 212, fig. 6.) 



NAVICULA OSCITANS A. Schmidt 



(Schmidt, Atlas, pi. 6. fig. 41.) 



What is called var. subundulata Cleve and Grove in Le Diatomiste, 

 page 67, plate 10, figure 10, is not a variety of this but a separate 

 species and is here included as N. suboscitans, which see. 



