44 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



The old genus Cerataulus can not be marked off from Biddulphia 

 by satisfactory characters. Both are normally of elongated or oval 

 valve outline, very convex and deep, and united by a wide girdle, so 

 that the frustule is usually deeper than wide; at the apices of the 

 bilateral valves are two massive processes or horns ; the markings are 

 frequently coarse and more or less radial, and spines, sometimes in 

 large number, are often superposed on the sculpture; these in some spe- 

 cies like Biddulphia Tieteroceros Grunow and Cerataulus turgidus Ehren- 

 berg, are massive, long and bifurcated at the tip ; the method of growth 

 of the two is the same; so that on the whole it is no wonder the same 

 diatom is assigned by one able diatomist to Biddulphia and another 

 equally able to Cerataulus, as in the case of Biddulphia radiata Roper 

 and Cerataulus smithii Ralfs. 



The Philippine specimens of the present species, B. petitii, vary 

 somewhat from the type form of Leuduger-Fortmorel, judged by his 

 sketchy figure and rather meager description; the horns being not to 

 one side of the long axis but bisected by it, the spines near the mid- 

 dle being not fewer and smaller but closer and larger, and the bead- 

 ing being not rectangular but radial. But comparison of the two 

 figures will show that these differences are not specifically important. 

 The type came from the near-by island of Java. 



BIDDULPHIA PULCHELLA Gray 



(Smith, Brit. Diat., pi. 44, fig. 321; Schmidt, Atlas, pi. 118, figs. 26-33.) 



This cosmopolitan species is known to be very variable both in 

 size and form. Small specimens, with deep valves and girdles, so 

 wide as to give a tubular form, are the prevailing ones in the Philip- 

 pine Islands. 



BIDDULPHIA PUNCTAT A Greville 



(Micro. Journ., 1864, pi. 11, fig. 10.) 



The type came from the fossil bed at Cambridge, Barbados. Boyer's 

 B. interrupts (Proc, Acad. Nat. Sci. Phila., 1S98, pi. 24, fig. 2.) is sim- 

 lar, but has radiating beads, spines at the center, and the interrupt- 

 ing arcuate bands do not fully cross the valve. 



BIDDULPHIA PYGMAEA, new name 



(Schmidt, Atlas, pi. 98, fig. 16.) 



This species is accurately illustrated in the above figure, and there 

 named Triceratium pulchellum Grunow. It is an evident Biddulphia, 

 but can not be transferred with its specific name because of B. pul- 

 chella Gray. It is therefore renamed. It is also what is called T 

 cornutum, var. pulchella Grunow, in Van Heurck's Synopsis, plate 

 108, figures 12-13, but this can hardly be united with Greville's T. 

 cornutum in the Microscopic Journal for 1861, page 45, plate 8, figure 8. 



