158 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Its names therefore are to be reckoned with; and the above has pri- 

 ority over S. mollis A. Schmidt, in the second reference above, the 

 date of which is 1897. The diatom is curiously unlike other Surirellae 

 in having the ribs extremely short around the margin, with no trace 

 of a separate median area or other markings; and it is practically iden- 

 tical with the so-called Campylodiscus anceps Castracane (Chall. Exp., 

 p. 66, pi. 16, fig. 2, 1886) which Janisch later called C. similis (Gaz. 

 Exp., pi. 19, fig. 8) because of the resemblance here noted. This 

 latter differs from S. schleinitzii merely in being circular instead of 

 figure 8 shaped, is perfectly flat instead of having the Campylodiscus 

 double curvature and, it may be incidentally mentioned, is probably 

 a constant and curious variety of this unique species. Both are 

 rather frequent in the Philippine Islands. 



SURIRELLA SIGNIFICANS, new species 



Plate 36, fig. 2 



Valve broadly elliptical; border double, that is, divided by a 

 median line into an outer and an inner half; heavy, marked with 

 coarse beaded crosslines; ribs or costae with broad, rectangular 

 outer ends overlapping the border and having two teeth or spines 

 next to the margin; proceeding inward from these ends the ribs are 

 narrow for about one-third their length, where they swell into a small 

 knot or joint and then continue as still narrower lines until they meet 

 the ribs of the opposite side or reach a small circular area in the 

 center of the valve; this last is exactly central, is bordered by a 

 sharply defined line or ridge, and is so perfectly hyaline as to appear 

 like a circular hole. Its size is in every case proportionate to the 

 size of the valve, being about one-sixth its transverse diameter. 



Length of valve, 0.066 to 0.103; width, 0.046 to 0.082 mm. 



Type.— Cut. No. 43690, U.S.N.M. 



SURIRELLA STUDERI Janisch 



Plate 35, fig. 4 

 (Janisch, Gaz. Exp., pi. 16, fig. 10.) 



My specimens exactly duplicate the type form figured in the above, 

 which I believe is the only illustration of this fine and rare diatom, 

 for which reason it is figured here. 



Unfortunately no locality is given for the type. 



SURIRELLA SULUENSIS, new species 



Plate 36, fig. 3 



Valve broadly elliptical, massive; border heavy, coarsely crosslined; 

 outer ends of the costae superimposed on the border, lozenge-shaped; 

 outer third of the costae made up of twin rows of fine transverse 

 lines, the remaining two-thirds thin, unmarked, narrowing down until 



