116 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



N. parallela Castracane (1886) would replace N. plicatula Grunow 

 (1894). But as there still may be some doubt about this identity 

 I accept Grunow's name and include here only the unnamed figure 

 given in the Report of the Challenger Expedition, plate 28, figure 13 

 The fact that Castracane saw a difference between this figure and 

 his N. parallela makes the decision to leave the latter out of this 

 combination a safe one, despite the suspicious similarity above noted. 

 I give here an illustration of the typical form with undulating 

 rhaphe and of the variety with straight rhaphe. 



NAVICULA PRAETEXTA Ehrenberg 



(Gregory, Diat., Clyde, pi. 1, fig. 11; Schmidt, Atlas, pi. 3, figs. 30-34; Van 

 Heurck, Synopsis, pi. 9, fig. 13.) 



This species is represented by many variations in the Philippine 

 Islands. 



NAVICULA PRISTIOPHORA Janisch 



(Schmidt, Atlas, pi. 70, fig. 72.) 



The only previously recorded locality for this species is Leton Bank. 

 Fricke's Index incorrectly makes it a variety of N. gemmata Greville. 



NAVICULA PROBABILIS A. Schmidt 



(Schmidt, Atlas, pi. 50, fig. 46.) 



Although the specific name is an implication of uncertainty on the 

 part of Schmidt, I think its separate rank is worth while. It is 

 another species found only at Campeche Bay and the Philippine 

 Islands. 



NAVICULA PRODIGA Mann 



(Mann, Diat., Alb. Voyages, p. 352, pi. 53, fig. 4.) 



The type specimen came from the Hawaiian Islands. 



NAVICULA PSEUDO-CLAVATA, new species 



Plate 25, fig. 2 



Valve broadly elliptical, with produced, rounded ends; sides in the 

 middle portion nearly straight; markings of very fine, closely set 

 rows of beading, radial and parallel to each oth r near the margin, 

 becoming wavy toward the center; the rows interrupted by long nar- 

 row hyaline spaces extending diagonally from near the apices on each 

 side the rhaphe toward but not reaching, the middle of the valve, 

 and also by a small flaring central stauros; rhaphe straight, ending 

 in beads at the middle and in minute hooks turned to the same side 

 at the apices. 



Length, 0.141; width, 0.073; 11.5 lines in 0.01 mm. 



With this may be compared N. transfuga Grunow in Cleve's Vega 

 Diatoms, plate 35, figure 15, from Seychelles Islands and a doubtful 

 variety of the same in Schmidt's Atlas, plate 204, figure 17. 



Type.— Cat. No. 43656, U.S.N.M. 



