TROPICAL PACIFIC FORAMINIFERA OF "ALBATROSS" 55 



recorded in the Indo-Pacific, and in the Philippine region, for example, 

 reaches very large size. It was very rare in the material from Samoa, 

 so that its range may be much more limited than seems probable 

 from the numerous records of its occurrence. 



Genus OPERCULINA d'Orbigny, 1826 



Opercidina d'Orbignt, Ann. Sci. Nat., vol. 7, p. 281, 1826. 



Synonyms: Nautilus (part) of authore; Lenliculiles (part) Defrance, 1822; 



Amphistegina (part) d'Orbigny, 1826; Nonionina (part) Williamson, 



1852; Nummulina (part) Parker and Jones, 1865. 



Genotype. — By designation, Lenticulites complanata Defrance. 



Test bilaterally symmetrical, planispiral, complanate, usually all 

 the coils visible from the exterior, earlier coils sometimes involute; wall 

 calcareous, perforate, smooth or ornamented with bosses; aperture 

 single, at the base of the apertural face, median. Lower Cretaceous 

 to Recent. 



There are numerous specimens of Operculina from the various 

 shallow-water collections. Specimens are not always so abundant 

 as one would wish, on account of the limited material, but they seem 

 to show, as was found in the collections from Samoa and particularly 

 those from the Philippine region previously studied, that there are 

 probably numerous localized species or varieties that with an exten- 

 sive study of the shoal-water material of the Pacific may be found to 

 have very definite distributions. It has usually been the custom to 

 follow Brady's Challenger Report, and refer the smooth forms to 

 Operculina complanata, and those which have beads and bosses on 

 the surface to var. granulosa. That such a simple arrangement does 

 not represent the true condition of the forms is apparent to anyone 

 who has studied any quantity of material from the Indo-Pacific 

 where this genus is still a common one. We have referred our mate- 

 rial to two species, one of which is rather large, somewhat inflated in 

 the middle, and while it is somewhat beaded in the early stages has 

 the sutures limbate and entire in the later portion. The other form 

 is marked by a depressed center in many cases, and there are large 

 beads or bosses as a dominant feature of the ornamentation. A 

 number of the forms are figured, but left under these two names until 

 someone may have the opportunity to study in further detail the 

 Indo-Pacific species of Operculina. 



OPERCUUNA GAIMAIRDI d'Orbigny 



Plate 13 



Operculina gaimairdi d'Orbigny, Ann. Sci. Nat., vol. 7, p. 281, no. 5, 1826. — 

 FoRNASiNi, Boll. Soc. Geol. Ital., vol. 22, pi. 14, fig. 4, 1903.— Cushman, 

 U. S. Nat. Mus. Bull. 100, vol.4, p. 375, 1921; Carnegie Inst. Washington 

 Publ. 342, p. 50, pi. 17, fig. 4, 1924. 



