FORAMINIFERA OF THE PHILIPPINE AND ADJACENT SEAS. 375 



The relations of the different species and varieties will be dis- 

 cussed in the pages that follow. 



OPERCULINA GAIMAIRDI d'Orbigny. 



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

 FoRNASiNi, Boll. Sec. Geol. Ital., vol. 22, 1903, pi. 14, fig. 4. 



Description. — Test of medium size, much compressed, complanate, 

 opaque; chambers 15 or less in the last-formed coil, curved, sutures 

 distinct, and the revolving suture fairly well shown; central area 

 somewhat enlarged in megalospheric specimens, the remainder of the 

 test marked by chains of beads along the sutures, the rest of the 

 chamber being smooth and unornamented. 



Diameter up to 3 mm., sometimes more. 



This species has occurred in the Philippines in the following 

 localities: Vicinity of Jolo; Sulu Archipelago; vicinity of Siasi; 

 Tawi Tawi Group; between Burias and Luzon; and in the Gulf of 

 Davao. Bottom temperatures are not given at any of the stations 

 at which it is recorded; the depths at which it is found range from 

 10 to 318 fathoms (18 to 582 meters). 



This seems to be a very definite species in the area and limited to 

 warm regions, as the table of distribution shows. 



The whole test is opaque, the ornamentation of the sutures showing 

 as darker lines on account of the transparency of that portion. There 

 is some variation in the width of the coil, and the granules of the 

 ornamentation may blend into confluent lines. 



Operculina gaimairdi — Material examined. 



