MILIOLIDAE — ORBICULINA; ORBITOLITES. 81 



Chapman's specimens from Funafuti, which are the types of this 

 species, do not closely resemble those found in the Tortugas collection, 

 nor are they so close to those figured by Brady in the reference 

 above as are our specimens. Until the completed test is found the 

 specimens may be provisionally referred to Chapman's species. It 

 would be interesting to know where Brady's specimens were from. 

 Little is known of the genus in the Atlantic, the other records being 

 all from the Indo-Pacific. 



Genus ORBICULINA Lamarck, 1816. 



Orbiculina compressa d'Orbigny. 



Orbiculina compressa d'Orbigny, in De la Sagra, Hist. Fis. Pol. Nat. Cuba. 1839. "Forami- 

 niferes," p. 66. pi. 8, figs. 4 to 7.— Cushman, Carnegie Inst. Wash., Pub. 291, 

 1919, p. 70, pi. 7, fig. 6; Proc. U. S. Nat. Mus.. vol. 59. 1921, p. 76, pi. 19, figs. 4 to 6. 



0. compressa, described by d'Orbigny, which makes the complete 

 circle of the test in its later chambers, is very common in the Tortugas 

 collection, perhaps more so than the following species. It is widely 

 distributed, at least in the West Indian region, d'Orbigny recording 

 it as rare in Cuba, more common in Guadeloupe and St. Thomas, 

 and abundant in Jamaica. I found it abundant off the north coast 

 of Jamaica, and fossil specimens occur in the Bowden Marl on the 

 south side of the same island. I have already shown the differences 

 in the early development of this and the following species (Bull. 71, 

 U. S. Nat. Mus., part 6, 1917, pp. 89-91). 



Orbiculina adunca (Fichtel and Moll). 



Nautilus aduncus Fichtel and Moll, Test, Micr., 1798, p. 115, pi. 23, figs, o to e. 



Orbiculina adunca Lamarck, Tabl. Ency. et Meth., 1816, p. 468, figs. 2 o to c— D'Orbigny, 

 in De la Sagra, Hist. Fis. Pol. Nat. Cuba, 1839, " Foraminiferes," p. 64, pi. 8, 

 figs. 8 to 16.— Cushman, Proc. U. S. Nat. Mus., vol. 59, 1921, p. 77. 



Specimens are all of large size and abundant at most of the sta- 

 tions. Orbiculina seems to reach a much greater development in 

 the West Indian region than in any other part of the world, it being 

 the characteristic large foraminifer at shallow and moderate depths, 

 replacmg in the West Indies the large Orbitolites, Heterostegina, and 

 Operculina of the East Indies. However, in the Eocene of the West 

 Indian region these genera, now so characteristic of the East Indian 

 region, were abundant and large, Orbiculina being a later develop- 

 ment. 



Genus ORBITOLITES Lamarck, 1801. 

 Orbitolites duplex Carpenter. 

 "Orbitoliles (duplex type)," Carpenter, Philos, Trans., 185G, p. 120, pi. 5, fig. 10; pi. 9, 



fig. 10. 

 Orbitolites duplex Carpenter, Rep. Challenger, "Orbitolites," 1883, p. 25, pi. 3, figs. 8 to 14; 

 pi. 4, figs. 6 to 10; pi. 5, figs. 1 to 10.— Cushman, Proc. U. S. Nat. Mus., vol. 59, 

 1921, p. 77. 



On the short eel-grass (Posidonia) this species is fairly abundant. 

 It also occurs in the bottom samples from most of the stations. 



