MARINE DIATOMS OF THE PHILIPPINE ISLANDS 123 



NAVICULA (DICTYONEIS) THUMII Cleve,. misnamed. 



(Cleve, Nav. Diat., vol. 1, pi. 5, fig. 33.) 



See under N. marginata Lewis. 



The separation of this form from the many variants of N. margin- 

 ata solely on the ground of its lacking a median constriction would 

 be at least debatable, were there not all possible gradations of this 

 one quality. The extremely constricted type is seen in N. strangu- 

 lata Greville (Micro. Journ., 1866, pi. 12, fig. 24) less sudden in con- 

 striction in N. jamaicensis Greville (fig. 23 of the same plate) then 

 comes Lewis's type (Schmidt, Atlas, pi. 160, fig. 21, followed by figs 

 30 and 31 of the same plate), and finally Cleve's figure above. All 

 have the same irregularly set beading, the same rhaphe, the same 

 marginal row of rectangular markings, simulating the marginal cham- 

 bers of Mastogloia, and the same central area. It is one of the most 

 widely distributed and (consequently ?) most variable of all the dia- 

 toms. Were Cleve's species valid a new specific name would be 

 needed to transfer it into Navicula on account of N. thumii Pantocsek 

 (Hung. Diat., 1886, vol. 1, pi. 10, fig. 85). 



NAVICULA TRANSLUCENS, new species 



Plate 26, fig. 9 



Valve convex, broadly lanceolate or spindle-shape, with small but 

 rounded apices; markings of very finely beaded, closely set lines 

 running diagonally outward, but less so toward the ends, where they 

 become more nearly transverse, approaching very close to the rhaphe 

 but leaving a thin hyaline median area; at the center this median 

 area is slightly broadened to form the oval hyaline nodule; on either 

 side and parallel with the margin the beading is interrupted by an 

 indistinct line running about midway between the sides and the 

 rhaphe; rhaphe straight, its inner ends joined together by a faint 

 ridge, so that it appears to run continuously across the oval hyaline 

 central nodule; outer ends of the rhaphe not reaching the apices of 

 the valve, very slightly bent at the tips, not terminating in beads. 



Length, 0.101-0.135; width, 0.028-0.040; 11-12.5 lines in 0.01 mm. 



This delicate species has close affinity with N. my Cleve (Nav. Diat., 

 vol. 2, pi. 1, fig. 17) from China and some likeness to N. belgicaV&n 

 Heurck (Belg. Antarct, pi. 1, fig. 9.) 



Type.— Cat. No. 43665, U.S.N.M. 



NAVICULA TURGESCENS, new name 



This is Diploneis platessa Cleve and Grove, in Naviculoid Diatoms, 

 volume 1 , page 97, plate 2, figure 6. That genus, as elsewhere stated, 

 is not accepted by Van Heurck, Schmidt, De Toni, and others, includ- 

 ing the author. But Navicula platessa is not available, being pre- 

 empted by Cleve in his New and Little-Known Diatoms, plate 1, 



