MABINE DIATOMS OF THE PHILIPPINE ISLANDS 65 



COSCINODISCUS ASTEROMPHALUS Ehrenberg 



(Ehrenberg, Mikrogeologie, pi. 18, fig. 45; Schmidt, Atlas, pi. 63, figs. 5, 12, 

 and pi. 113 ,fig. 23.) 



A species of cosmopolitan distribution, and although showing cor- 

 respondingly wide variation, too frequently mixed with other names 

 which ought to be kept separate, as C. biangulatus A. Schmidt, 

 C. omplialanthus Ehrenberg, C. centralis Ehrenberg, etc. Of course 

 species are hard to outline sharply in this huge genus because of the 

 comparative simplicity of pattern on which all are built; and it is 

 therefore largely a matter of conjecture where the specific boundaries 

 will run. Thus, although the type form of C. oculus-iridis of Ehren- 

 berg is quite different from the type form of this species, one meets 

 with intermediate forms that might as well go into one species as 

 the other. 



COSCINODISCUS CENTRALIS Ehrenberg 



(Ehrenberg, Mikrogeologie, pi. 18, fig. 39; pi. 22, fig. 1; Gregory, Diat. Clyde, pi. 

 11, fig. 49.) 



COSCINODISCUS CERVINUS (Brightwell) Ralfs 



See Hyalodiscus cervinus Brightwell. 



COSCINODISCUS CILIATUS, new species 



Plate 14, fig. 3 



Valve circular, barely convex until near the margin, then strongly 

 so; covered with radiating rows of closely set beading uniform in 

 in size; the three or four beads in each row nearest to the margin 

 are perhaps slightly smaller than the others; no hyaline central space, 

 or definite rosette ; two rows of fine but evident spines close to the 

 margin, pointed outward, those in one row generally alternating with 

 those in the other; rim strong and hyaline. 



Diameter, 0.082-0.087 mm. 



Karsten's C. Jiorridus (Valdivia Exp., pi. 5, fig. 9) is nearest to this 

 handsome form. 



Type.— Cat. No. 43612, U.S.N.M. 



COSCINODISCUS CONCINNUS W. Smith 



(Quart. Journ. Micro. Sci., 1858, pi. 3, fig. 12; Pritchard, Inf., pi. 5, fig. 89; 

 Schmidt, Atlas, pi. 113, fig. 8.) 



This species is of very wide distribution and of bewildering com- 

 plexity of synonyms. There is also a wide range of difference in size 

 and in the fineness of the areolation. The prevailing Philippine 

 Islands form is small but robust and coarsely netted. Whether or 

 not the original type has the two blunt marginal processes, set apart 



