96 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Length, 0.113 to 0.143; width, 0.037 to 0.038; 8.2 lines in 0.01 mm. 



This beautiful form has affinities with several species, like Navicula 

 (Pseudo-Ampliiprora) stauroptera Bailey, called N. arctica by Cleve in 

 his Arctic Diatoms, plate 3, figure 13; but especially with N. jugata 

 Cleve (New and Little-Known Diat. , p. 13, pi. 3, fig. 39). It differs 

 in its more prismatic outline, its very acute apices, its radial and 

 irregular beading, and in the sharp central incurve of its hyaline lines, 

 with the two strong beads at the central area. As Cleve (Nav. Diat. , 

 vol. 1, p. 71) unites his species with N. pensacola, a form impossible 

 to include with mine, the dissimilarity of this and N. jugata is empha- 

 sized. Cleve's species is from the Gallapagos Islands and its variety 

 from Florida. 



I can not see the advantage of the new genus Pseudo-Arnphiprora, 

 created by Cleve to accommodate his N. jugata and some similar 

 species, which would include this one also. The chief distinction, 

 the elevated central portion extending the length of the valve, is not 

 at all infrequent in Navicula, for example, N. carinifera Grunow, and 

 the side lines and stauroslike central area are nothing more than a 

 union of the frequent N. lyra style of marking with a carinate central 

 elevation. That it indicates a well-marked subgeneric division is ad- 

 mitted, but to separate it from Navicula is to create confusion for 

 diatom students. 



Type.— Cat. No. 43639, U.S.N.M. 



NAVICULA BLEISCHIANA Janisch and Rabenhorst 



(Janisch and Rabenhorst, Diat., Hond., p. 9, pi. 2, fig. 10; Schmidt, Atlas, pi. 

 50, figs. 22-25.) 



Written N. bleischii on the plate and is so given by Schmidt. 



NAVICULA BOMBOIDES A. Schmidt 



(Schmidt, Nordsee Diat., pi. 1, fig. 2; Schmidt, Atlas, pi. 13, figs. 36-40.) 



NAVICULA BRANCHIATA.new species 



Plate 21, fig. 2 



Valve figure eight (8) in shape, that is, round-panduriform; cross- 

 barred with smooth and wavy costae, slightly connivant near the 

 middle, but progressively curved from the middle as they approach 

 the two ends, where they attain an almost longitudinal direction; 

 wholly unbeaded except for a single bead in the slightly enlarged 

 marginal end of each costa; median area on either side of rhaphe 

 broad and bordered with a single row of imperfect beads or blotches 

 corresponding in number and position to the adjacent rows of costae; 

 widest transverse diameter of each half of the valve exactly midway 

 between the center and the end. 



Length, 0.093; width, 0.028; costae, 6.2 in 0.01 mm. 



