72 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



an unlikeness to what we picture as a " Navicula" and make its new 

 classification a convenience to the taxonomist. Nor does it seem to 

 me to signify that each of these marks of distinction may be found sepa- 

 rately in some aberrant species of Navicula; for the same contention 

 would destroy a good many accepted genera. 



CYMATONEIS DEF1NITA, new species 



Plate 15, fig. 1 



Valve prismatic-elliptical, its side nearly straight from the wide 

 middle to the blunt apices, these being not at all produced; the nar- 

 row elliptical median area only slightly elevated above the rest of 

 the valve at its two extremities and none at its middle; the entire 

 valve, including the median area, covered with coarse rows of bead- 

 ing, the beads closely set in each row, the rows well separated, the 

 beading so evenly arranged as to show false longitudinal striation as 

 well as the cross striation; this striation tranverse at the middle, 

 increasingly radial toward the apices, and there arranged fan wise; 

 rhaphe straight, terminating outwardly in two long straight spines, 

 its inner ends actually overlapping, the tips bent to opposite sides. 



Length, 0.110; width, 0.046; lines, 4.2 in 0.01 mm. 



Type.— Cat. No. 43616, U.S.N.M. 



CYMATONEIS LACUNATA, new species 



Plate 15, fig. 2 



Valve oval, strongly convex, modified by a shoulder close to each 

 apex, the apices bluntly rounded ; markings of transverse, closely set 

 rows of beading, leaving a narrow, somewhat sigmoid, perfectly hya- 

 line central area, which is bisected by the sigmoid rhaphe, at the two 

 extremities of which are two strong pointed spines, obliquely turned 

 outward; beading so regularly spaced in the rows that they fall into 

 longitudinal as well as transverse lines. 



Length, 0.053-0.096; width, 0.029-0.045; lines, 6.5-7.5 in 0.01 mm. 



Type.— Cat. No. 43617, U.S.N.M. 



CYMATONEIS SUFFLATA, new species 



Plate 15, fig. 3 



Valve elliptical or subrectangular, with barely convex sides, quickly 

 rounded up to the produced papillate apices; central area elevated, 

 extending to the apices, marked like the rest of the valve, except for 

 a narrow hyaline area on either side of the rhaphe and a slightly 

 enlarged hyaline area about the central nodule; these valve markings 

 strong, of closely set rectangular beads in transverse rows, becoming 

 slightly curved and radial toward the apices, showing longitudinal 

 lines, which become slightly incurved toward the apices and thereby 



