MARINE DIATOMS OF THE PHILIPPINE ISLANDS 13 



the radii characteristic of Actinocyclus, but very obscurely, or in 

 some specimens apparently lacking; no central hyaline area; bead- 

 ing adjacent to the margin a trifle more compact and slightly smaller 

 than within ; center of the valve raised into a low conical elevation 

 one-third to one-quarter the diameter, surrounded by a shallow de- 

 pressed ring one-sixth to one-eighth the diameter, with the outer area 

 raised to the same focal plane as that of the central cone; pseudo- 

 nodule large, robust, surrounded by a narrow hyaline space and 

 placed on the extreme outer margin. 



Diameter 0.08 to 0.18 mm. 



Type.— Cat. No. 43564, U.S.N.M. 



ACTINOCYCLUS OBSCURUS Rattray 



{Rattray, Rev. Actinocyclus, p. 187, pi. 11, fig. 5.) 



ACTINOCYCLUS PRUINOSUS Castracane 



(Castracane, Chall. Exp., pi. 4, fig. 2, as defined in Rattray, Rev. Actin., p. 167.) 



ACTINOCYCLUS PUNCTULATUS Castracane 



(Castracane, Chall. Exp., p. 146, pi. 16, fig. 3.) 



This is the same as Peragallo's A. nebulosus (Diat., France, pi. 113, 

 figs. 10-11.) 



ACTINOCYCLUS ROTULA Brun 



(Brun, Espec. Nouv., p. 6, pi 17, fig. 5.) 



Specimens typical according to Brun's figure are frequent; but 

 this species may be only a variety of A. sparsus (Gregory) Rattray. 



ACTINOCYCLUS SPLENDENS Rattray 



(Rattray, Rev. Actinocyclus, p. 168, pi. 11, fig. 14.) 



ACTINOCYCLUS STICTODISCUS 



See under Stictocyclus, new genus. 



ACTINOCYCLUS SUBTILIS (Gregory) Ralfs 



(Pritchard, Infusoria, p. 835; Van Heurck, Synopsis, pi. 124, fig. 7; H. L. 

 Smith, Types, No. 14.) 



Genus ACTINODISCUS Greville 



ACTINODISCUS SCHLEINITZII (Janisch) Mann 



(Schmidt, Atlas, pi. 149, fig. 19; Janisch, Gaz. Exp., pi. 20, figs. 18-19.) 



Specimens of this diatom were found in several of the Philippine 

 Islands dredgings, but in no case was there present an Actinoptychus 

 or other circular diatom to which it could be referred as "an inner 

 valve," to confirm the suggestion of Van Heurck (Treat., p. 501). 

 But the creation of a new genus for this form, as is done by Schmidt 

 (Atlas, pi. 149, fig. 19), where it is named Gyroptychus contabulatus 

 A. Schmidt, is quite unnecessary. It should be classed under Actino- 

 discus as defined in Van Heurck's Treatise, p. 497. Compare it 



