38 BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



chambers in the whorl, sutures limbate, the intermediate portions of 

 the surface depressed, the inner margin of the whorl often granulose, 

 in face view about five times as long as wide; aperture simple. 



Diameter about 0.5 mm. 



Distribution. — The only North Pacific stations from which this 

 species has been recorded are given by Brady in the Challenger Report, 

 off the Philippines in 95 fathoms, Hongkong Harbor in 7 fathoms, 

 south of Japan on the Hyalonema ground in 345 fathoms. 



I have the species from Albatross station D 4970 in 500 fathoms off 

 Japan. 



Genus HETEROSTEGINA d'Orbigny, 1826. 



Heterostegina d'Orbigny (type, H. depressa d'Orbigny), Ann. Sci. Nat., vol. 7, 

 1826, p. 305.— H. B. Brady, Rep. Voy. Ohallenger, Zoology, vol. 9, 1884, 

 p. 745. 



Description. — Test compressed, especially the last-formed whorl, 

 the early whorls often embracing and fairly thick, lenticular in side 

 view; chambers numerous, subdivided into chamberlets by trans- 

 verse partitions and visible from the exterior; secondary canal system 

 developed and comparable to Operculina; aperture consisting of a 

 row of pores on the outer face of the chamber, one pore for each of 

 the chamberlets. 



The chamberlets are not directly connected with one another in 

 the same chamber but are connected by the previously formed aper- 

 tures with the adjacent chamberlet of the previous chamber. Often 

 the central portion of the test is decidedly thickened while the last- 

 formed whorl is extremely thin. 



The genus is characteristic of shallow water of the Tropics. 



HETEROSTEGINA DEPRESSA d'Orbigny. 



Plate 19, fig. 5. 



Heterostegina depressa d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 305, No. 2, 

 pi. 17, figs. 5-7; Modeles, No. 99. — Parker, Jones, and H. B. Brady, Ann. 

 Mag. Nat. Hist., ser. 3, vol. 16, 1865, p. 34, pi. 3, fig. 100.— H. B. Brady, 

 Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 746, pi. 112, figs. 14-20 — 

 Egger, Abh. kon. bay. Akad. Wiss. Mtinchen, CI. n, vol. 18, 1893, p. 433, 

 pi. 20, figs. 34, 35.— Chapman, Journ. Linn. Soc, Zool., vol. 28, 1900, p. 18, 

 pi. 3, figs. 6, 7. — Millett, Journ. Roy. Micr. Soc, 1904, p. 606. — Rhumbler, 

 Zool. Jahrb., Abteil. Syst., vol. 24, 1906, p. 74. 



Description. — Test in section lenticular, early chambers embracing 

 and thickened, later whorls thin, periphery with a thin keel, cham- 

 bers subdivided into chamberlets by transverse partitions, the cham- 

 berlets near the interior border of the whorl being much larger than 

 those of the peripheral portion, division apparent from the exterior. 



Diameter up to 5 mm. or more. 



