118 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



marks this marginal bend and extends around the entire valve, 

 including its apices; entire surface of the valve, including the vertical 

 sides, dotted with small widely separated beads, showing a slight 

 tendency to form transverse rows; a small oval hyaline area at the 

 center; rhaphe very slightly sinuous, its middle terminations distant 

 and bent in opposite directions. 



Length, 0.090-0.099; width, 0.030-0.033 mm. 



This delicate and peculiarly ornamented species reminds one of 

 N. (Alloioneis) grundleri Cleve and Grunow, also found in the Philip- 

 pine Islands material and figured in Cleve's West India Diatoms, plate 

 2, figure 10, and here recorded under the new name N. inexacta Mann, 

 and illustrated on plate 22 figure 7 for comparison as a Philippine 

 Islands form. 



Type.— Cat. No. 43659, U.S.N. M. 



NAVICULA KAEANA (Castracane) Cleve 



(Castracane, Chall. Exp., p. 25, pi. 15, fig. 3.) 



Cleve's idea (Nav. Diat., vol. 2, p. 69) that this species may be a 

 variety of N. yarrensis Grunow can not be commended. In general 

 shape, in the character of its rhaphe and in its costal markings it is 

 clearly distinct. The original type form also came from the Philippine 

 Islands. 



NAVICULA RECTANGULATA Gregory 



(Gregory, Diat., Clyde, p. 7, pi. 9, fig. 7; Donkin, Brit. Diat., pi. 10, fig. 5; Van 

 Heruck, Synopsis, Supp., pi. A, fig. 7.) 



NAVICULA RETINENDA A. Schmidt 



(Schmidt, Atlas, pi. 212, fig. 17.) 



Schmidt's contention that this form offers satisfactory distinctive 

 mark from N. liber W. Smith seems to be correct. The type specimen 

 came from the not distant Sumbawa, East Indies. 



NAVICULA RETROSTAUROS, new species 



Plate 25, fig. 5; plate 26, figs. 1-2 



Valve quite convex, narrow oval or spindle-shaped, the sides slop- 

 ing from the middle gently to the rounded ends; covered with fine 

 closely set lines diagonal to the long axis and rather obscurely beaded, 

 the beading of each line being slightly irregular, resulting in a faint 

 wavy appearance in the sculpture; interrupted by a faint but persis- 

 tent longitudinal line on each side near to the margin and parallel 

 with it; at the center a strong stauros, at first narrow but suddenly 

 broadened out at the outer ends into triangular enlargements and 

 just touching the two faint longitudinal side lines above mentioned; 

 this stauros perceptibly sunken in the surface of the valve, so that 

 its vertical side boundaries are strongly accentuated; rhaphe a trifle 



