100 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



becoming narrower toward the ends; two narrow bands midway 

 between the sides and the middle, curving with the curve of the 

 sides, except at the center of the valve, where they bend inward 

 toward the central nodule; similar wavy beading on either side of 

 the rhaphe, narrow at the apices, then broadening until near the 

 center; rhaphe straight, with hooked apical ends, both bent toward 

 the same side; a conspicuous ocellus set to one side of the central 

 nodule. 



Length, 0.090-0.132; width, 0.068-0.087; lines (margin), 11 in 0.01 

 mm. 



The nearest affinity to this rather frequent Philippine diatom is 

 N. caliginosa Cleve and Grove (Le Diat., vol. 1, pi. 10, fig. 9) from 

 Macassar Strait. 



Type.— Cat. No. 43643, U.S.N.M. 



NAVICULA DELECTA, new species 



Plate 24, figs. 5-7 



Valve panduriform, considerably narrowed at the middle, apices 

 slightly prolonged, acute; widest diameter of each half midway be- 

 tween middle and apex; markings of widely spaced, smooth or 

 slightly granular costae, beginning with enlarged ends, a short dis- 

 tance inward from the margin and running nearly to the rhaphe, their 

 length being in strict proportion to the width of the valve, so that the 

 outer ends are everywhere equidistant from the margin ; those near the 

 middle slightly reflexed, absolutely transverse only at the widest 

 diameter of the two halves and becoming more diagonal toward the 

 apices; a row of short costae forming a border around the entire 

 margin and extending downward over its curved edge; equal in num- 

 ber to and continuous with the longer costae, from which they are 

 separated by a narrow hyaline space; rhaphe strong, straight, its 

 middle ends well separated, its outer ends reaching the apices, with 

 an evident median area on either side. 



Length, 0.068-0.124; width, 0.028-0.035; lines, 4 in 0.01 mm. 



There is an easily seen relationship between this ornate and grace- 

 ful species and N. bartholomei Cleve (W. I. Diat., p. 6, pi. 1, fig. 5) 

 which, however, is closer to N. powellii Lewis than to this form and 

 is so classified in Fricke's index. N. oartholomei lacks the produced 

 and acute apices of his species; its costae are broader, fewer, are all 

 transverse, and " a row of small granules" replaces the marginal 

 costae of N. delecta. Cleve's parallel between his species and vari- 

 eties of N. marginata Lewis (N. strangulata Greville, etc.) is very 

 fanciful. Nor, despite the similarity, should Fricke's classification of 

 it as a variety of iV. powellii be considered necessary. Frequent. 



Type.— Cat. No. 43644, U.S.N.M. 



