58 



BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



and there occurs as rare specimens only ; 21 fathoms, Guam Anchorage, 

 Ladrone Islands; 18 fathoms, Vavau Anchorage, Tonga Islands; and 

 Makemo Lagoon, Paumotu Islands. I also have specimens from three 

 Albatross stations in deeper water, as shown in Table 29. 



Table 29. — Heterostegina depressa — material examined 



HETEROSTEGINA SUBORBICULARIS d'Orbigny 



Plate 17, Figures 6a, h 



Heterostegina suhorbicularis d'Orbignt, Ann. Sci. Nat., vol. 7, p. 305, 1826. — 

 FoRNASiNi, Boll. Soc. Geol. Ital., vol. 22, pi. 14, fig. 6, 1903.— Cushman, 

 U. S. Nat. Mus. Bull. 100, vol. 4, p. 385, 1921; Carnegie Inst. Washington 

 Publ. 342, p. 51, 1924. 



Test free, central portion thickened and involute, peripheral portion 

 thin, especially toward the periphery, subdivisions of the chambers 

 not appearing until the flange is developed; wall smooth. Diameter, 

 up to 2.5 mm; thickness, 1 mm. 



This species was described by d'Orbigny from the Sandwich Islands, 

 and another form of the species from the Marianas and from Port 

 Jackson. I have also recorded it from the Philippines and from 

 Samoa. In the present collections the only specimens are from 

 Albatross stations, data for which are given in Table 30. In these 

 specimens the umbonate region is very strongly convex, while in the 

 following species it is broad and flattened although the entire central 

 portion is also somewhat thickened. 



Table 30. — Heterostegina suhorbicularis — material examined 



