MARINE DIATOMS OF THE PHILIPPINE ISLANDS 93 



diatoms — the arrangement above indicated seems to me the best. It 

 should be added that some undoubted members of Stephanopyxis are 

 destitute of spines, as for instance, Stephanopyxis turris, var. arctica 

 forma inermis Grunow (F. Jos. Land, pi. 5, fig. 18) . The superficially 

 similar S. robusta Leuduger-Fortmorel above referred to has a large 

 hyaline central area (Hyalodiscus?) outside of which are radiating 

 lines of fine beading. It is also a much larger diatom and resembles 

 more closely my Hyalodiscus hirtus, new species. 

 Type.— Cat. No. 43637, U.S.N.M. 



MELOSIRA GOWENII A. Schmidt 



Plate 20, figs. 3-4 

 (Schmidt, Atlas, pi. 176, figs. 4-6; name on pi. 180.) 



This appears to be a marine phase of M. undulata Kiitzing. It 

 may, however, be accorded specific rank, as the Philippine Islands 

 specimens are clearly the same as the type form found at San Fran- 

 cisco, Calif. My specimen shows the umbilicuslike center common 

 in M. undulata. It is rather close to what Schmidfe in his Atlas, 

 plate 180, figure 22, calls M. bisereata Ehrenberg, which, however, is 

 not the same as that diatom as shown in Ehrenberg's Mikrogeologie, 

 plate 33, section 12, figure 18. In the girdle illustration here given 

 note the difference in contour of the two adjacent valves. 



Diameter of valve, 0.084; depth of frustule, 0.060 mm. 



MELOSIRA INCOMPTA, new species 



Plate 20, fig. 5 



Frustule an elongated cylinder terminating at each end in a trun- 

 cated cone, the whole exactly resembling a gelatine capsule; a shallow 

 groove around each valve where it joins the narrow girdle; both 

 valves, but not the girdle, sparingly and irregularly spotted with 

 small beads becoming somewhat denser toward the ends. 



Length of frustule, 0.073; width of frustule, 0.017 mm. 



This apparently unfinished diatom is not at all uncommon in 

 Philippine Islands dredgings. 



Type.— Cat. No. 43638, U.S.N.M. 



MELOSIRA MADAGASCARENSIS A. Schmidt 



(Schmidt, Atlas, pi. 181, fig. 79.) 



This anomalous diatom is placed here for convenience, although its 

 being a Melosira is very doubtful. It is abundant in Philippine Is- 

 lands material and ranges from small tubular frustules with rounded 

 apices (valves) to comparatively huge specimens, massively built 

 with frustule^ little if at all longer than broad. Although the coarse, 

 irregular blotches which constitute the marking of the vertical sides 

 (flanges) and convex tops of the valves are separated into a central 



