494 PKOCEEDINGS OF THE jSTATIOjSTAL MUSEUM Vol. S3 



O. dia is associated with Lepidocyclina nianteUi (Morton) and is a 

 characteristic species of the lower Oligocene, whereas O. forresti is 

 associated with species of Lepidocyclina of middle Oligocene age. 



OPERCULINOIDES TUXPANICUS, new species 

 l*LATi: 37, Figures 4-9 



Test small, fragile, compressed, completely involute, without orna- 

 mentation except for traces of the septal lines. Diameter from outer 

 edge of aperture through center ranges from 1.7 to 3.2 mm ; diameter 

 at right angles to aportural plane ranges from 1.5 to 3 mm; thick- 

 ness through center ranges from 0.3 to 0.5 mm. The test is thickest 

 through the center and slopes gradually to the rather sharply 

 rounded periphery. 



A section of a specimen about 1.6 mm in diameter has 3 coils, with 

 19 chambers in the final volution. Another specimen about 2.5 mm 

 m diameter has Si/o coils, with 20 chambers in the final whorl. 



The chamber walls are gently recurved except near the periphery, 

 where they are sharply recurved. Some of the chamber walls vary 

 from this pattern, as shown in the figures. These exhibit a gradual 

 and regular recurvature throughout their length. The incorpora- 

 tion of two types of curvature in the same test gives the chambers 

 an irregular appearance and shape. 



Cotypcs.—V.^.'^M. no. 495191. 



Locality. — Roundtop, just southeast of the Plaza, City of Tuxpan, 

 Veracruz, Mexico (M 76 S) ; collected by D. li. Semmes. 



Geologic horizon. — Tuxpan formation of Miocene age. 



*■ LITERATURE CITED 



Cole, W. Storus, and Poxton, Gerald Mungo. 



1930. Foraminifera of the Murianua limestone. Florida State Geol. Surv. 

 Bull. 5, pp. 19-G9, 7 pis. 

 y AUG HAN, Thomas Waylakd. 



1928. New species of Opcrculina and DiscocjjcJina from the Ocala lime- 

 stone. 19th Ann. Rep. Florida State Geol. Surv., 1926-27, pp. 15G- 

 164, 2 pis. 



