MARINE DIATOMS OF THE PHILIPPINE ISLANDS 41 



BIDDULPHIA INDICA (Ehrenberg) Roper 



(Micro. Journ., 1859, pi. 1, figs. 20-22.) 



BIDDULPHIA INFORMIS, new species 



Plate 9, figs. 2, 3 



Valve convex, elongated, naviculoid, broadened at the middle and 

 with wedge-shaped ends, covered with scattered beads irregularly 

 distributed, the two horns at the extreme apices; inside (girdle) view 

 the horns are seen to rise perpendicularly from the apices, the outer 

 and straight side being the extremity of the valve, the inner side 

 sloping backward to the valve surface; girdle relatively broad and 

 hyaline, except for a single row of minute beads along each edge. 



Length of valve, 0.066-0.087; width of valve, 0.016-0.018 mm.; 

 depth of frustule, 0.033 mm. 



This singularly crude diatom was found in two dredgings but was 

 infrequent in both. Its girdle view reminds one of the doubtful 

 Plagiogramma van JiuercJcii Grunow (Van Heurck, Synopsis, p 1 - ^6, 

 fig. 4). 



Type.— Cat, No. 43594, U.S.N.M. 



BIDDULPHIA INSIGNIS (Greville) Mann 



(Micro. Journ. , 1861, p. 75, pi. 9, fig. 5; Schmidt, Atlas, pi. 78, fig. 3.) 



BIDDULPHIA INVERTA, new species 



Plate 9, fig. 4; plate 10, figs. 2, 3 



Valve triangular, its sides straight or barely concave; center a 

 domelike convexity separated from the broad bases of the three horns 

 by three deep sinuses that appear in face view as three narrow hya- 

 line bands uniting to form an inner triangle in reversed position to 

 that of the valve; the whole surface of the valve, except the tips of 

 the horns and the three hyaline sinuses, loosely covered with large, 

 crudely formed beads showing an imperfectly radial arrangement ; in 

 side view the apparently simple topography of the valve surface is 

 seen to be a highly complicated series of elevations and depressions; 

 the bases of the massive horns are separated from the domelike center 

 by deep sinuses, their tips rounded, incurved, and covered with fine, 

 closely, and regularly set beads; a deep groove runs around the base 

 of the valve (next to the girdle) ; on each half of the girdle, which is 

 very wide, a single row of large beads along the line of its attach- 

 ment to the valve, below this a few large scattered beads and toward 

 the bottom of each half similar beads closely set in vertical rows, that 

 is, transverse to the girdle, six to eight beads long. 



Diameter of valve (apex to middle of opposite side), 0.169-0.287 

 mm.; height of frustule, 0.265-0.282 mm. 



