130 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



PLAGIOGRAMMA DISTINCTUM, new species 



Plate 29, fig. 3 



Valve narrow spindle-shaped, distended at the middle; the central 

 space is a narrow, tran verse, hyaline rectangle, heavily outlined; the 

 two terminal spaces are thimble-shaped, heavily outlined, faintly 

 dotted; exclusive of these three spaces, the valve is covered on 

 either side with diagonal rows of beads, the spaces between being 

 wider than the rows; the beading of the sides appoach inwardly, but 

 leave an evident median longitudinal line (pseudorhaphe) . 



Length, 0.208; width, 0.040; 2.6 lines in 0.01 mm. 



This diatom might be looked upon as a not at all obese variety of P. 

 obesum Greville as figured in the Quarterly Journal of Microscopical 

 Science for 1859, plate 10, figure 12, except that the beading on Gre- 

 ville's species is in strictly transverse, not diagonal, rows which are not 

 widely separated, as they are in the above. Its nearest relative is, 

 however, P. constriction Greville (So. Pac. Diat., pi. 1, fig. 8), especi- 

 ally as figured Schmidt's Atlas, plate 211, figure 10, from Cebu, in 

 which the diagonal and wider spaced rows of beads are closely simi- 

 lar. The absence of any constriction should probably justify their 

 separation. Compare also the incorrectly named P. gregorianum, var. 

 robusta Brun in Diatomees Japon, plate 9, figure 7. 



Type.— Cut. No. 43668, U.S.N. M. 



PLAGIOGRAMMA GREGORIANUM Greville 



(Micro. Journ., 1859, pi. 10, fig. 1; Van He.urck, Sj^nopsis, pi. 36, fig. 2.) 

 It is not well to disturb this well-known name for the uncertain 



identity of it with Denticula staurophora Gregory (Diatoms of the 



Clyde, p. 497, pi. 10, fig. 37). 



PLAGIOGRAMMA NANKOORENSE Grunow 



(Grunow, Reise F. Novara, p. 95, pi. 1A, fig. 8; Schmidt, Atlas, pi. 210, fig. 31.) 



Castracane names this Glyphodesmis challenger ensis in his Report 

 of the Challenger Expedition, plate 18, figure 13, and in Leuduger- 

 Fortmorel's Diatomees Ceylan, plate 5, figure 59, it is called P. ceylan- 

 ense Leuduger-Fortmorel. 



PLAGIOGRAMMA OBESUM Greville? 



See remarks under P. distinctum, new species. 



PLAGIOGRAMMA PAPILIO Cleve and Grove 



(Le Diat., vol. 1, pi. 8, fig. 17; Schmidt, Atlas, pi. 211, fig. 13.) 

 This and P. Atomus Greville are closely alike. The type speci- 

 men came from the near-by Macassar Straits. 



