STUDIES IN FOKAMINIFERA 



35 



Porticiilaaphaera mexicana (Cushman), emended 



Plate 6, Figures 8-9b 



Glohigertna mexicana Cushman, Contr. Cushman Lab. Foram. 

 Res., vol. 1, No. 3, p. 6, pi. 1, figs. 8a-b, 1925. 



Test free, subglobiilar, of medium size, early portion 

 in a low trochospiral coil with five inflated chambers per 

 whorl, final chamber hemispherical, much inflated and 

 strongly embracing and enveloping the tunbilical region 

 of the early coil, larger in size than the entire previous 

 portion of the test; sutures generally distinct and de- 

 pressed; waU calcareous, coarsely perforate, radial in 

 structure, thin and delicate in the early portion, but 

 wall of final embracing chamber very thick, with a sec- 

 ondary layer of comparable thickness covering the re- 

 maining exposed portion of the earlier whorls and some- 

 what obscm'ing the chamber contacts but leaving open 

 the sutural apertures, surface finely spinose, the elongate 

 delicate spines visible on earlier chambers in the in- 

 terior of dissected specimens, but broken from the ex- 

 terior of the fossil shells; primary aperture in the early 

 portion interiomarginal, umbilical, an extremely large 

 opening, with smaller arched secondary sutural open- 

 ings on the spiral side as in Globigerinoides, the primary 

 aperture of the early portion covered by the final em- 

 bracing chamber, which has only the numerous small 

 arched, sutm-al secondary apertures (as many as 25) 

 completely encircHng its basal margin. 



Greatest diameter of figured hypotype 0.65 mm. 

 Other specimens range from 0.42 to 0.83 mm. in great- 

 est diameter. 



Remarks: Porticulasphaera mexicana was originally 

 described from the upper Eocene Tantoyuca formation, 

 Vera Cruz, Mexico. It was recorded as Globigerinoides 

 mexicana (Cushman) by Beckmann (1953, p. 393, pi. 25, 

 figs. 15-19) from the Oceanic formation of Barbados. 



Ttpes and occurrence: Holotype (Cushman Coll. 

 4334) from the upper Eocene Tantoyuca formation, 

 Palacho Hacienda, south of Panuco-Tampico railroad, 

 State of Vera Cruz, Mexico. Figm-ed hypotype 

 (USNM P3901), figured dissected hypotype (USNM 

 P3902), and unfigured hypotypes (USNM P3903 and 

 P3906) from the Eocene Navet formation. Penitence 

 Hill marl, Olobigerinatheka barri zone, in a block in the 

 Oligocene Nariva formation, Pointe-a-Pierre, Trinidad, 

 B. W. I. 



Unfigured hypotypes (USNM P4855) from the Glo- 

 bigerina facies of the Middle Eocene Guayabal forma- 

 tion ("Lower Chapapote") in Tierra Amarilla Well No. 

 25, at 1,200 feet, Vera Cruz, Mexico. From E. Wright 

 Barker. 



Unfigured hypotypes (USNM P3904) from the Navet 

 formation (Penitence Hill marl), Town Hall site, San 

 Fernando, Trinidad, B. W. I. 



Unfigured hypotypes (USNM P3905) from the 

 Oceanic formation (Lower Mount Hillaby member), 

 Mount Hillaby section, Barbados, B. W. I. Collected by 

 J. P. Beckmann. 



Genus Candeina d'Orbigny, 1839 



Plate 6, Figures lOa-11 



Candeina d'Obbignt, Foraminifferes, in de la Sagra, Histoire 

 physique, politique et naturelle de I'lle de Cuba, p. 107, 

 1839. 



Type species: Candeina nitida d'Orbigny, 1839. 

 Fixed by monotypy. 



Test free, trochospiral, relatively high spired; cham- 

 bers globular to hemispherical; sutures depressed, 

 radial to curved; waU calcareous, finely perforate, 

 radial in structure, surface smooth; primary aperture 

 in the very early stage interiomarginal, umbiUcal. later 

 in development smaller secondary sutural apertures 

 occur on each side of the primary aperture; in adult 

 tests there is no primary opening and the small rounded 

 sutural secondary apertures almost completely surround 

 the later chambers. 



Remarks: Candeina differs from Globigerina d'Or- 

 bigny in lacking the umbilical primary aperture in the 

 adult, and in having the nmnerous rounded sutural 

 secondary apertures. It differs from Globigerinoides 

 Cushman in lacking the umbilical primarj' aperture and 

 in having numerous small sutural secondary openings 

 on both spiral and umbilical sides of the test, instead of 

 having a relatively few larger secondary sutural aper- 

 tures on the spiral side only. 



Candeina passes through a Globigerina stage and a 

 Globigerinoides stage in its ontogenetic development, as 

 can be seen by a dissection of the test. 



Hofker (1954, p. 151) stated that Candeina has a 

 reduced toothplate, but the specimens we dissected 

 show nothing that could be so construed. The upper 

 border of the aperture is merely slightly thickened, as is 

 often true of Globigerina. 



Types and occurrence: Figured hypotjT^e (USNM 

 P3924) of Candenia nitida d'Orbigny from Albatross 

 Station 2660, lat. 28°40'00" N., long. 78°46'00" W., 

 depth 504 fathoms. Figured hypotype of dissected 

 specimen (USNM P3923) of C. nitida from Albatross 

 Station D.2754, lat. 11°40'00" N., long. 58°33'00" W., 

 at a depth of 880 fathoms. 



Range: Miocene to Recent. 



Genus Orbulina d'Orbigny, 1839 



Plate 7, Figures 1-5 



Orbulina d'Orbigny, ForaminifSres in de la Sagra, Histoire phy- 

 sique, politique et naturelle de I'lle de Cuba, p. 2, 1839. 



Candorbulina Jedlitschka, Verh. Naturf. Ver. BrUnn, vol. 

 65, p. 20, 1934. (Type species: Candorbulina universa 

 Jedlitschka, 1934. Fixed by monotypy.) 



Biorbulina Blow, Micropaleontology, vol. 2, No. 1, p. 69, 1956. 

 (Type species: Globigerina bilobala d'Orbigny, 1846. Fixed 

 by original desgination and monotypy.) 



Type species: Orbulina universa d'Orbigny, 1839. 

 Fixed by monotypy. 



Test free, generally spherical and composed of a 

 single chamber, rarely 2- or 3-chambered, or specimens 



