228 ll'PER CRETACEOUS-LOWER TERTIARY FOR AM INIFER A 



!957^ Globorotalia pseudomenardii Bolli : 77, pi. 20, figs. 14-17. 



? 1959 Globorotalia pseudomenardii Bolli ; Nakkady : 462-463, pi. 4, figs. $a-c. 



19606 Globorotalia pseudomenardii Bolli ; Bolli & Cita : 26-27, pi. 33, figs. -za-c. 



1961 Globorotalia pseudomenardii Bolli ; Said & Kerdany : 329, pi. 1, figs. $a-c. 



? 1961 Globorotalia pseudomenardii Bolli ; Bermudez : 1,298-1, 300, pi. 15, fig. 9. 



? 1962 Globorotalia pseudomenardii Bolli ; Hillebrandt : 126-127, pi. 12, figs. 5«-c, 6a, b. 



Description. (Specimen, PI. 17, figs, ya-c.) Test small, weakly biconvex, 

 compressed, coiled in a low trochospire ; dorsal side slightly raised, ventral side 

 moderately inflated ; equatorial periphery roughly ovoid, elongate, distinctly lobate ; 

 axial periphery angular, sharply acute, pinched out, with a fine, but distinct, entire 

 keel ; chambers, 12, arranged in 2 sinistrally coiled whorls ; the initial chambers are 

 small, slightly inflated, globigerine and increase slowly in size ; the last whorl is 

 composed of 5, roughly lenticular, weakly inflated, compressed chambers which 

 increase very rapidly in size ; on the ventral side, the 5, roughly lenticular chambers 

 are moderately inflated ; sutures on the dorsal side strongly curved, depressed ; on 

 the ventral side they are almost straight, radial and strongly depressed ; umbilicus 

 small, shallow and open ; aperture interiomarginal, extraumbilical-umbilical, a long 

 narrow arch covered by a delicate, flaring lip ; wall calcareous, perforate ; surface 

 smooth. 



Dimensions of described specimen. 



Maximum diameter = 0-30 mm. 

 Minimum diameter = 0-20 mm. 



Thickness = 0-14 mm. (of last chamber) 



Main variation. 



1. Chambers 12-18, arranged in 2-3 whorls. 



2. Coiling predominantly sinistral (of 125 specimens picked at random, 79 



coiled sinistrally). 



3. Chambers in the last whorl 4-6, most commonly 5. 



Remarks. This species was quite often described in the past as G. membranacea 

 (Ehrenberg), a nomen nudum. It is distinguished by its smooth, weakly biconvex, 

 compressed, elongate test ; its fine, entire keel ; distinctly acute axial periphery; 

 curved, depressed dorsal sutures and radial, incised, ventral ones ; its small umbili- 

 cus ; narrow elongate aperture, and delicate flaring lip. 



Loeblich & Tappan (1957a) described as G. pseudomenardii Bolli, forms which are 

 completely different from the type specimens of Bolli and from the known hypotypes, 

 while the form described by Olsson (i960) is most probably G. emilei sp. nov. 



Globorotalia pseudomenardii is believed to have evolved from G. ehrenbergi Bolli in 

 earliest Upper Paleocene time by the development of the entire keel, the rapidly 

 increasing chambers in the last whorl, and the distinctly acute, pinched-out axial 

 periphery ; although its evolution from G. emilei into G. woodi is not excluded. 



Hypotypes. P.45622. 



Horizon and locality. Figured specimens, from sample No. 39, Gebel Owaina 

 section. 



