92 BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



Distribution. — Brady records this species from the North Pacific 

 only from among the Philippines. The only material I have from 

 this region is collected by the Tuscarora in Honduras Bay. 



Brady records the species from about various East Indian Islands, 

 and it is interesting to note that in the Challenger material it is not 

 given from the Honolulu Reefs. Bagg records it from two Albatross 

 stations but an examination of his material from both these stations 

 shows that the specimens are Orbitolitcs marginalis and not Orbiculina. 

 They resemble the flattened compressed Orbiculina compressa, but 

 the central portion is not involute, the early chambers being all 

 visible as in typical Orbitolites marginalis. I have failed to find 

 Orbiculina in the Hawaiian region, although I have had but a small 

 amount of shallow water material. 



Genus ORBITOLITES Lamark, 1801. 



Orbitolites Lamarck, Syst. Anim. sans Vert., 1801, p. 376 (Type 0. complanata 

 Lamarck). — H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 210. 



Description.— Test typically discoidal, the early chambers, in the 

 microspheric form at least, following the proloculum and Cornuspira- 

 like second chamber, arranged in a gradually widening spiral, followed 

 by chambers extending in length and becoming annuli; chambers 

 divided into chamberlets, each with one or more apertures on the 

 rim of the test. 



A rather full description is given of the development as the species 

 are discussed and it need not be considered here. 



ORBITOLITES MARGINALIS (Lamarck). 

 Plate 38, figs. 1, 2. 



Orbulites marginalis Lamarck, Hist. Nat. Anim. sans Vert., vol. 2, 1816, p. 196, 



No. 1. 

 Orbiculina (Orbitolitcs) complanata Williamson, Trans. Micr. Soc. London, ser. 1, 



vol. 3, 1851, p. 115, pi. 17, fig. 8; pi. 18, figs. 9, 10. 

 Orbitolites marginalis Carpenter, Philos. Trans., 1856, p. 192, pi. 9, figs. 1-4, 



etc.; Rep. Voy. Challenger, Zoology, pt. 21, 1883, p. 20, pi. 3, figs. 1-7; pi. 4, 



figs. 1-5.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 214, 



pi. 15, figs. 1-5. 



Description. — Test circular or nearly so, flattened, chambers numer- 

 ous, in a single layer, in the adult becoming annular, completely 

 surrounding the periphen^ of the test; wall smooth, the area about each 

 chamberlet slightly depressed, the center of the chamberlet slightly 

 protuberant; apertures in a single row along the periphery of the 

 test; the chamberlet communicating with one another by lateral 

 openings just behind the periphery, these in turn opening backward 

 into the preceding annular chamber. 



Diameter, up to 5 mm., but usually smaller. 



