NO. 4 



PLANKTONIC FORAMINIFERA — CIFELLI 



21 



Pustules or blunt spines are distributed over the entire surface but 

 are concentrated mostly beneath the aperture of the final chamber. 

 The young form of this species does not have an umbilicus, and 

 the ventral cone is much lower than in the adult form. The truncated 

 conical shape of the test with an umbilicus is achieved during the 

 ontogeny, at about the end of the second whorl, where there is a 

 sudden relative increase in size of the lateral dimensions of the 

 chamber. The lateral slope at this stage is less acute than in the early 

 stage and tends to flare out with respect to the axial dimension of 

 the chamber (fig. 3). 



Fig. 3. — Relative increase in lateral slope of Globorotalia truncatulinoides. 

 Left, mature form. Right, immature form. 



In the material studied, this species showed a decided preference 

 for sinistral coiling. However, specimens were not available in suf- 

 ficient numbers from the summer and fall traverses to determine 

 possible seasonal differences in coiling ratios. 



Distribution. — Globorotalia truncatulinoides was the dominant 

 species in the southern stations (JJ through OO) in the winter. The 

 highest frequency was 55 percent at station JJ. At other seasons this 

 species was rare or absent at most stations, the highest frequency 

 being 3 percent in the fall at station 5. 



Genus CANDEINA d'Orbigny, 1839 

 CANDEINA NITIDA d'Orbigny 



Plate 5, figure 4 



Candeina nitida d'Orbigny, 1839, in De la Sagra, Hist. Phys. Pol. Nat. Cuba, 

 Foraminiferes, p. 108, pi. 2, figs. 27-28. — Bradshaw, 1959, Contr. Cushman 

 Found. Foram. Res., vol. 10, pt. 2, p. 32, pi. 7, fig. 19.— Be, 1959, Micro- 

 paleontol., vol, 5, No. 1, pi. 2, figs. 19, 20. 



