NEW TERTIARY EORAMINIFERA VAUGHAN AND COLE 493 



that two species should be recognized. Of the two, antiguensis is the 

 larger, it has more numerous chambers, and in a median section the 

 chamber walls tend to be sigmoid in plan. 



OPERCULINOIDES FORRESTI, new species 



Plate 37, Figuees 1-3 



Test small, thin, compressed, with the sides nearly parallel; aver- 

 age specimens have a diameter from outer edge of aperture through 

 center of test of about 2.5 mm; diameter at right angles to line 

 through aperture, about 2.3 mm ; the largest specimen observed had 

 a diameter of about 3 mm. The thickness of an average specimen is 

 about 0.3 mm. The surface is without ornamentation, except for 

 the slightly raised recurved septa, wdiich are more pronounced 

 toward the periphery of the test. 



A specimen with a diameter of 1.9 mm has 3 whorls, with 16 

 chambers in the final coil ; another 2.6 mm in diameter has 4 whorls, 

 with 21 chambers in the final whorl. The maximum number of 

 chambers observed in the final volution was 24. 



The chamber walls are but slightly curved for most of their length, 

 radiating outward at 90° from the inner wall. As they approach 

 the periphery they are sharply and strongly recurved, so that the 

 end of one septum nearly touches the point of strong curvature of 

 the adjacent septum. 



In most specimens there is a very gradual increase in height as the 

 chambers are added. 



Cotypes.—V.^.'^M. no. 495193. 



Localities. — Cotypes, tilted beds, east of Lynch 's, Antigiia; cliff, 

 east of Gaynor's, Antigua, and many other Antiguan localities; 

 collected by W. R. Forrest. 



Geologic horizon. — Middle Oligocene, Antigua formation. 



Remxirks. — This species resembles closely O. dia Cole and Ponton 

 (1930, p. 37) described from the Marianna limestone. They are 

 similar in possessing rather fragile, compressed tests. Detailed 

 comparison of fom^esti with topotype specimens of dia at once indi- 

 cates that there are important differences. O. forresfi is usually 

 larger, has fewer chambers in the final volution, has a different type 

 of curvature of the chamber walls and raised septal lines. Cole and 

 Ponton's figures and topotype specimens of dia show that in that 

 species the proximal parts of the chamber walls are gently curved, 

 whereas in their distal parts the curvature is strong. The sutures 

 of O. fon^esti are nearly straight from the center for about three- 

 fourths of their length, but near the periphery they are strongly and 

 sharply recurved. 



