MARINE DIATOMS OF THE PHILIPPINE ISLANDS 173 



TRINACRIA TRIPEDALIS, new species 



Plate 39, figs. 2-3 



Valve triangular, with blunt, rounded apices, the verticle legs at 

 the three angles appearing in this view as three oval or subtriangu- 

 lar disks, each showing a shadowy internal ring, but otherwise hyaline; 

 exclusive of these, the valve is ornamented with small widely sepa- 

 rated beads, set in four concentric circles, with large, elongated, equi- 

 distant beads or bars along the three sides of the valve; in side 

 (girdle) view the beading of the valve is seen to extend downward 

 toward the girdle only one or* two rows, being followed by a hyaline 

 space, with a single row of beading on its edge where it joins the 

 girdle; the latter is beaded with closely set transverse lines; the ver- 

 tical legs are short, stout, rounded, and marked with scattered bead- 

 ing, their terminal awns three parted. 



Height of valve measured from apex to middle of opposite side, 

 0.037-0.047; width of frustule, 0.039 mm. (average). 



There is marked similarity between this and some figures of so- 

 called Triceratium, as T. pauperculum Greville (Trans. Micro. Soc, 

 1865, pi. 6, fig. 26) and T. dulce Greville (Trans. Micro. Soc, 1866, 

 pi. 2, fig. 20), but as only a side (girdle) view can indicate their true 

 generic position, a union of this merely similar form with them 

 would be unwise. 



Type.— Cat. No. 43696, U.S.N.M. 



Genus TROPIDONEIS Cleve 



The diatoms included in this genus were weeded out of Amphiprora 

 by Cleve. I believe they form a valid genus and relieve Amphiprora 

 of some species resembling true Amphiproras in only a general way. 

 Cleve defines and gives reasons for this genus in his Naviculoid Dia- 

 toms, part 1, page 22. Van Huerck in his treatise, page 263, accepts 

 the genus and its three subdivisions Orthotropis, Plagiotropis, 

 and AmpJioropsis. 



TROPIDONEIS APPROXIMATA Cleve 



(Cleve, Nav. Diat., vol. 1, p. 26, pi. 3, figs. 20-21.) 



TROPIDONEIS FRAGILIS (Tempere and Brun) Mann 



(Brun, Diat. Jap., pi. 9, fig. 14.) 



This is rather close to Amphiprora membranacea (Cleve, Diat. Java, 

 pi. 2, fig. 18), renamed Tropidoneis membraneacea by Cleve, in his 

 Naviculoid Diatoms (vol. 1, p. 24). 



TROPIDONEIS JAVANICA (Cleve) Mann 



(Cleve, Nav. Diat., vol. 1, p. 21, pi. 2, fig. 22.) 



Cleve puts this in the genus Auricula. After carefully examining 

 several specimens I can find no justification for this. The geographi- 

 cal proximity of the type location, Java, to the Philippine Islands 

 is to be noted. 



