IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 129 



suggesting that the two keeled specimens are juvenile forms while the single keeled 

 ones are mature. Since then G. rosetta rosetta has been quite often confused with 

 G. area Cushman. G. marginata (Reuss), G. stuarti (de Lapparent) and G. cretacea 

 Cushman (= G. mariei Banner & Blow i960). 



Tilev (1951, 1952) included G. rosetta rosetta (Carsey) in the synonymy of G. 

 cretacea Cushman 1938 ( = G. mariei Banner & Blow i960) although the former has 

 priority. Bronnimann & Brown (1956) partially substantiating Tilev's observation, 

 stated that " Examination of the holotype of Globotruncana rosetta (Carsey), in the 

 Carsey collection at the University of Texas, reveals that it possesses two keels in 

 the early chambers of the last whorl which are very close together. In the ante- 

 and penultimate chambers the two keels join ". These two authors also added 

 " In an examination of the holotype of Git. cretacea Cushman, two keels, very close 

 together, were observed in all chambers of the last whorl. It is intermediate 

 between Git. lapparenti Brotzen and Git. rosetta (Carsey) . It seems to be an incipient 

 form of Git. rosetta, for all transitions exist between forms corresponding to the holo- 

 types of Git. rosetta and Git. cretacea. We suggest that the forms which exhibit two 

 keels, close together in all chambers of the last whorl be referred to Git. cretacea 

 Cushman, and that the forms which exhibit two keels close together in the early 

 chambers of the last whorl and only one keel in the final one or two chambers be 

 referred to Git. rosetta (Carsey) ". They also included G. leupoldi Bolli in the 

 synonymy of G. rosetta (Carsey). However, the present study has clearly shown 

 that G. rosetta rosetta (Carsey), G. cretacea Cushman (= G. mariei Banner & Blow) 

 and G. leupoldi Bolli are separate and distinct forms. 



Gandolfi (1955) described as new subspecies of G. rosetta (Carsey), two distinct 

 forms which he named Globotruncana rosetta insignis Gandolfi and Globotruncana 

 rosetta pettersi Gandolfi, thus changing the name of the present form to Globotruncana 

 rosetta rosetta (Carsey) . He did not state whether his G. rosetta rosetta had a double 

 keel on the early part or not, and his G. rosetta insignis appears to be synonymous with 

 G. fareedi sp. nov., as mentioned earlier (p. 101). Gandolfi also described as G. 

 bollii n. sp., a form which may possibly be a junior synonym of G. rosetta rosetta 

 (Carsey). Moreover, he suggested that G. rosetta rosetta evolved from G. thalmanni 

 thalmanni through G. bollii into G. rosetta pettersi and G. rosetta insignis, while 

 Berggren (1962) suggested that G. rosetta evolved from G. mariei. However, the 

 evolutionary development of G. rosetta rosetta is not yet clearly understood. It may 

 have evolved from G. concavata (Brotzen) or from G. ventricosa White as suggested 

 by the morphological features and stratigraphical ranges of these species, but no 

 direct evidence was recorded. On the other hand, G. rosetta rosetta probably evolved 

 into G. gansseri gansseri (Bolli) as well as giving rise to G. rosetta pettersi. 



Hypotype. P.45552. 



Horizon and locality. Figured specimen from sample No. 16, W. El-Sharaw- 

 na section. 



Stratigraphical range. Carsey (1926) described the holotype of G. rosetta 

 from the upper Taylor marl (Upper Campanian of Texas), but apparently she had 



