76 SHALLOW-WATER FORAMINIFERA OF TORTUGAS REGION. 



This species, originally described by d'Orbigny as common in 

 shallow water off Cuba and Jamaica, is widely distributed in the 

 West Indian region and occurs in considerable numbers in the 

 Tortugas collection. It seems to be widely distributed across the Indo- 

 Pacific, reaching its best development in waters less than 30 fathoms 

 in warm seas. There is a certain amount of variation in the number 

 and prominence of the costae, but in general its characters are very 

 constant. 



Triloculina quadrilateralis d'Orbigny. 



Triloculina quadrilnUralis d'Orbigny, in De la Sagra, Hist. Fis. Pol. Nat. Cuba, 1839, 

 "Foraminiferes," p. 173, pi. 9, figs. 14 to 16. — Cushman, Proc. U. S. Nat. Mus., 

 vol. 59, 1921, p. 71, fig. 11 (in text). 



Test somewhat longer than broad, in the adult the exterior composed of 

 3 chambers, generally quadrangular in outUne, the periphery slightly convex, 

 but the angles acute and projecting, sides concave; wall with numerous fine, 

 incised short lines; aperture oblong, with a single elongate tooth, projecting 

 slightly above the outline of the aperture. 



Length of the Tortugas specimens up to 0.65 mm. 



D'Orbigny described this species from Cuba, and I found speci- 

 mens from the north coast of Jamaica which were evidently the 

 same species. It has been found at most of the stations in the 

 Tortugas region, and therefore is probably widely distributed in the 

 general West Indian region in comparatively shallow water. The 

 quadrilateral condition is only developed in the adult, the younger 

 chambers often being simply carinate or sharply angled. In the 

 adult specimens the aperture may become much more elongate 

 than is shown in d'Orbigny's figure and the lip extends out somewhat 

 beyond the peripheiy of the test. 



Triloculina bicarinata d'Orbigny. 



(Plate 12, Figure 7.) 



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

 nifferes," p. 158, pi. 10, figs. 18 to 20. 



Test longer than broad, trilocuUne, typically with the chambers with a 

 truncate periphery, the angles somewhat extended; chambers distinct; sutures 

 somewhat depressed; surface ornamented by reticulations both on the sides 

 and on the outer angles; aperture elongate, with a definite thin lip, slightly 

 everted, tooth elongate, narrow, extending above the outline of the aperture. 



Length of the Tortugas specimens up to 1.4 mm. 



This species, which d'Orbigny described from Cuba, maj"- be dis- 

 tinguished from the preceding, not only by the shape of the test, 

 but also by the difference in reticulations. In T. bicarinata the 

 reticulations are as shown by d'Orbigny, more or less rectangular, 

 and much coarser than in T. carinata. In that species the retic- 

 ulations are much smaller and are either rounded or elliptical and 

 much more regularly placed. 



