174 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



TROPIDONEIS LATA Cleve 



(Cleve, Nav. Diat., vol. 1, p. 28, pi. 3, figs. 3-4.) 



TROPIDONEIS LEPIDOPTERA (Gregory) Cleve 



(Micro. Journ., 1857, pi. 1, fig. 39; Gregory, Diat., Clyde, pi. 12, fig. 59.) 



TROPIDONEIS MAXIMA (Gregory) Cleve 



(Gregory, Diat., Clyde, pi. 12, fig. 61.) 



TROPIDONEIS MEMBRANACEA Cleve 



(Cleve, Diat., Java, pi. 2, fig. 18; Cleve, Nav. Diat., vol. 1, p. 24.) 

 Note the resemblance to this mentioned under T. fragilis. 



TROPIDONEIS OBLONGA (Greville) Cleve 



(Micro. Journ., 1863, pi. 1, fig. 15.) 



Cleve says (Nav. Diat., vol. 1, p. 26) that this "seems to be akin to 

 T. maxima." If this means they are specifically the same, the speci- 

 mens I have do not uphold that supposition. There is enough differ- 

 ence between them to justify both names. 



TROPIDONEIS PHANTASMA, new species 



Plate 39, fig. 4 



Valve extremely convex and laterally compressed, so that the view 

 obtained is always that of the side (girdle), the rhaphe occupying 

 the sharp curved ridge of the dorsal side; the two halves on either 

 side of the rhaphe are of unequal width, so that, seen from the side, 

 one overlaps the other, the edge of the wider appearing to be convex 

 and that of the narrower slightly concave; the rhaphe is strong, the 

 central nodule (in middle of the dorsal ridge) somewhat depressed; 

 the two terminal nodules are located at the extreme tips of the pointed 

 apices ; markings of transverse lines of very fine closely set beading, 

 frequently interrupted by hyaline spaces, giving to the valve a de- 

 cidedly mottled appearance. This species is rare. 



Length of valve, 0.148; depth of valve, 0.056; lines 17.2 in 0.01 mm. 



Type.— Cat. No. 43697, U.S.N.M. 



TROPIDONEIS VAGA, new species 



Plate 39, fig. 5 



Valve lanceolate, at its middle barely constricted laterally but 

 deeply depressed transversely with tapering, somewhat cuneiform 

 ends and rounded apices ; an elevated longitudinal median area, one- 

 third the width of the valve, extending from the center to the two 

 apices; rhaphe strong, straight, its halves terminating at both ends 

 in beads, the central ends well separated; the markings are of closely 

 set, coarse, transverse, beaded lines; there is a small hyaline space at 

 the central nodule, and a slight separation of the lines on either side 



