FOEAMINIFERA OF THE NORTH PACIFIC OCEAN. 



19 



Fig. 21. — Discorbis 

 operculars (d'or- 



B I G N Y ) . X 66. 

 (ADAPTED FROM 



d'Orbigny's ORIGI- 

 NAL FIGURE.) 0, 

 DORSAL MEW; 6, SIDE 

 VIEW. 



Discorbina opercularis Parker and Jones, Quart. Journ. Geol. Soc, vol. 28, 1872, 

 p. 114.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 650, 

 pi. 89, figs. 8, 9.— Egger, Abh. kon. bay. Akad. Wiss. Miinchcn, CI. n, vol. 18, 

 1893, p. 389, pi. 15, figs. 73-75.— Millett, Journ. Roy. 

 Micr. Soc, 1903, p. 701. — Rhumbler, Zool. Jahrb., Abt. 

 Syst., vol. 24, 1906, p. 69.— Chapman, Journ. Quekett 

 Micr. Club, ser. 2, vol. 10, 1907, p. 135. 



Description. — Test nearly circular, very much com- 

 pressed, plano-convex, dorsal side slightly conical, 

 ventral side nearly flat; peripheral margin rather 

 sharp; chambers numerous, about seven to nine in 

 the final whorl, very long and narrow, spirally ar- 

 ranged ; sutures distinct but slightly if at all depressed ; 

 wall on dorsal side often showing rather prominent 

 granulation; borders of the chambers often slightly 

 carinate; ventral side, especially near the center, 

 with very prominent tubercles somewhat radiately 

 arranged and smaller toward the periphery; aperture 

 a very narrow elongate slit at the ventral border of the chamber. 



Diameter 0.40-0.50 mm. 



Distribution. — The only published record for this species in the 

 North Pacific is that of Rhumbler, who obtained two specimens in 

 material from Chatham Island. I have had the 

 species only from Albatross station D4807 in 44 

 fathoms off Japan. 



DISCORBIS PULVINATA (H. B. Brady). 



Plate 7, fig. 2. 



Discorbina pulvinatalL. B. Brady, Rep. Voy. Challenger, 

 Zoology, vol. 9, 1884, p. 650, pi. 88, fig. 10a, b — 

 Egger, Abh. k6n. bay. Akad. Wiss. Miinchen, CI. 

 ii, vol. 18, 1893, p. 391, pi. 15, figs. 33-35.— Mil- 

 lett, Journ. Roy. Micr. Soc, 1903, p. 701. — Rhum- 

 bler, Zool. Jahrb., Abt. Syst., vol. 24, 1906, p. 70.— 

 Sidebottom, Mem. and Proc. Manchester Lit. and 

 Philos. Soc, vol. 52, No. 13, 1908, p. 14, pi. 5, fig. 4. 

 Description. — ' ' Test broadly ovate or subglobu- 

 lar, somewhat depressed ; composed of a few more 

 or less inflated segments, about three in the final 

 convolution; superior face rugose externally; in- 

 ferior deeply excavated at the umbilicus and ornamented with 

 radiating granulose lines. 



"Diameter l/90th inch (0.28 mm.)." 



Distribution. — Rhumbler records a single specimen of this species 

 from Laysan. This is the only North Pacific record for the species. 



Fig. 22.— Discorbis pulvi- 

 nata (H. B. Brady). X 

 100. (After Brady.) a, 



DORSAL VIEW; b, VENTRAL 

 VIEW. 



