Diagnosis. - A Globotruncana with concavo-convex test, weakly developed double keel, wide peripheral band, rough surface and very wide umbilicus.

Description - Test large, roughly ovoid in outline, concavo-convex, coiled in a very low trochospire; dorsal side gently concave with the early whorls depressed and the last chambers slightly sloping towards the central part of test, ventral side inflated and moderately protruding; equatorial periphery roughly ovoid, moderately lobate with two widely spaced, delicately beaded marginal keels which are slightly masked by the surface rugosity; axial periphery subrounded, subtruncate; chambers on the dorsal side 15, arranged in 2½ dextrally coiled whorls; the initial chambers are small, weakly inflated, globigerine, and increase slowly in size; they are followed by relatively large, subglobular, compressed chambers which increase slightly more rapidly in size; the last whorl is composed of 5½ large, crescentic, compressed chambers which are slightly tilted towards the central part and increase slowly in size; on the ventral side the chambers are 5½, subglobular, slightly elongated in the direction of coiling, strongly inflated, moderately protruding, very loosely coiled and increase slowly in size; sutures on the dorsal side slightly curved, depressed in the early part, strongly curved, raised and delicately beaded in the last whorl; on the ventral side the sutures are straight, radial and strongly incised; umbilicus hexagonal in outline, very wide, relatively shallow, covered by complex tegilla; primary apertures interiomarginal, umbilical; tegilla, with accessory apertures, reasonably well preserved; wall calcareous, perforate except for the imperforate keels, peripheral band and tegilla; surface rough, covered with large papillae which are slightly reduced towards the last chamber; the two marginal keels are delicately beaded, the dorsal one is always well-developed but the ventral is sometimes almost masked by the surface rugosity; the two keels slightly diverge from each other and enclose an irregular, relatively wide peripheral band.

Main variation. - Ch ambers on the dorsal side 13-18. arranged in 2h-3 whorls, usually dextrally coiled. but sinistral forms occasionallyoccur (of 67 specimens picked at random, I coiled sinistrally). Chambers in the last whorl 5-7 increasing slowly to moderately 111 stze.QQ"
Remarks. - Globotruncana bahijae El-Naggar is morphologically rather similar to each of the following Globotruncana species, all of which, except the last, appear in stratigraphically older strata:

• Globotruncana concavata (Brotzen) [Rotalia concavata. 1934]. 
• Globotruncana fundiconulosa Subbotina. 
• Globotruncana (Rugoglobigerina) pennyi subpennyi Gandolfi. 
• Globotruncana repanda Bolli. 
• Globotruncana arabica El-Naggar.

However, it is distinguished from G. concavata (Brotzen) by its more concave dorsal side and less protruding ventral one, widely spaced keels, chambers which increase less rapidly in size and rough surface.
It differs from G. fundiconulosa Subbotina in its more concave dorsal side, less strongly developed marginal keels, chambers which increase more rapidly in size and radial depressed ventral sutures.
It is more closely related to the form described by Gandolfi (1955) as G. (Rugoglobigerina) pennyisubpennyi, but differs from it in its concave dorsal side and less protruding ventral one and by its widely spaced marginal keels. It might possibly have evolved from the latter subspecies which appears to be a true Globotruncana (not a Rugoglobigerina). although Gandolfi 's description does not allow a definite decision.
Globotruncana bahijae is distinguished from both G. repanda Bolli and G. arabica by its compressed test, less protruding ventral side, greater number of chambers and widely spaced keels.""

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