FORAMINIFERA OF THE PHILIPPINE AND ADJACENT SEAS. 385 

 Heterostegina depressa, var. tubercalata — Material examined. 



HETEROSTEGINA SUBORBICULARIS d'Orbigny. 



Heterostegina saborbictdaris d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 305. — 

 FoRNAsiNi, Boll. See. Geol. Ital., vol. 22, 1903, pi. 14, fig. 6. 



This species, not described by d'Orbigny, but later figured in his 

 planches inedites as published by Fornasini, seems to be the common- 

 est in this region. Its whole appearance is very different from that 

 of H. depressa, it being much thicker, strongly biconvex in the central 

 portion, then later developing a compressed, broadly flaring portion 

 which is thin near the periphery. The entire test is smooth and the 

 subdivisions do not appear until a considerable amount of the test 

 is built. These then appear near the periphery and gradually 

 develop across the chambers of the test. The sutures in the early 

 portion of the test are nearly straight, and remind one of those in 

 Operculina venosa, which the early part of the test strongly resem- 

 bles. The peripheral edge of the test is acute, except in very large 

 specimens, where the border becomes thickened and somewhat cari- 

 nate. Specimens attain a growth of 8 mm. or more. The species 

 s abundant in warm, shallow waters, where it often makes up a large 

 proportion of the bottom. 



D'Orbigny described this species from the Hawaiian Islands as va- 

 riety A, and variety B from the Marianna Islands, and from Port Jack- 

 son, Australia; therefore it is evidently a species of Indo-Pacific regions. 

 Alcoholic specimens which were collected at D5179, off Romblon, 

 show a green color, probably due to large numbers of symbiotic 

 algae which occur in the test. Heron-Allen and Earland also note 

 this character in H. depressa from the Kerimba Archipelago. 



This species has occurred in the following localities: China Sea^ 

 off southern Luzon; Sulu Archipelago, near Basilan Island; vicinity 

 of Jolo; vicinity of Siasi; near Tawi Tawi; off Romblon; between 

 Burias and Luzon; Gulf of Davao; and Buton Strait. 

 182152—20 25 



