MARINE DIATOMS OF THE PHILIPPINE ISLANDS 31 



Genus AULACODISCUS Ehrenberg 



AULACODTSCUS KINKERI A. Schmidt 



(Schmidt, Atlas, pi. 106, figs. 4-5.) 



It is very questionable if Rattray's uniting this as a variety with 

 A. margaritaceus Ralfs is an advantage (see Rattray, Rev. Aulaco., 

 p. 352). 



AULACODISCUS MACRAEANUS Greville 



* (Micro. Journ., 1862, pi. 2, fig. 4; Schmidt, Atlas, pi. 104, fig. 2.) 



AULACODISCUS MARGARITACEUS Ralfs 



(Schmidt, Atlas, pi. 37, figs. 4-5; pi. 104, figs. 7-8; pi. 105, figs. 1, 2, 4.) 



AULACODISCUS ORIENT ALIS Greville 



(Micro. Journ., 1864, pi. 2, fig. 6; Schmidt, Atlas, pi. 34, figs. 1, 3.) 

 Although the type of this species is clearly different from A. ore- 



gonus Harvey and Bailey, a perfect series of intermediate forms 



bridges the gap between the two. 



AULACODISCUS PRETIOSUS, new species 



Plate 6, fig. 2 



Valve circular, having a round hyaline central area from which 

 proceed about 11 radial lines bordered by single rows of fine, closely 

 set beads; each hyaline line broadening at the margin into a small 

 circular space, in the center of which is placed a minute sessile hem- 

 ispheriod process ; the rows of beading between the radii generally 

 parallel to within one-third of the margin, then converging toward 

 the central row; the short secondary rows are suddenly multiplied 

 around the outer one-quarter of the radius of the valve, the beading 

 being smaller as it becomes more crowded, so that the outer one- 

 quarter appears as an external band; the center of every bead is 

 marked by a minute dot or prickle; the surface of the valve is nearly 

 flat, the central part barely depressed, and the areas between the 

 eleven marginal processes only slightly concave. 



Diameter, 0.129 mm. 



The nearest species are those shown in Schmidt's Atlas (pi. 107, 

 fig. 6) A. oregonus, var. sparsus-punctata Grunow and (pi. 107, figs. 

 5-6) A. voluta coeli Brun. 



Type.— Cat. No. 43583, U.S.N.M. 



AULACODISCUS RECEDENS, new species 



Plate 6, fig. 3 



Valve circular, flat to within one-fifth of the margin, thence curv- 

 ing rapidly downward ; a hyaline central area one-sixth the radius in 

 diameter, from which proceed eight broad, hyaline radii to within 

 35035—25 3 



