in the esna-idfu region, nile valley, egypt 101 



Main variation. 



i. The test may be strongly or weakly biconvex. 



2. Chambers 18-24 arranged in 3-4 whorls, (all the specimens studied coiled 



dextrally) . 



3. The beading of the sutures and the keel may be heavy throughout or may fade 



out gradually towards the last chamber. 



4. The rate of growth may be slow and constant, leading to a regular increase in 



chamber size, or it may be rapid in the later stage, producing relatively 

 bigger chambers in the last whorl. 



5. The dorsal surface of each of the chambers in the last whorl (not the dorsal 



side of the test) is flat, slightly convex, or even slightly concave. 



6. The umbilicus is moderate to large and the ventral sutures are either slightly 



or strongly depressed. 



Remarks. Globotruncana fareedi sp. nov. morphologically resembles both 

 G. stuarti stuarti (de Lapparent) and G. esnehensis Nakkady & Osman. It is dis- 

 tinguished from the former by its equally biconvex test, lobate periphery, quad- 

 rangular rather than trapezoidal chambers on the dorsal side ; short, depressed 

 radial sutures on the ventral side and less tangential ones on the dorsal ; its much 

 wider umbilicus and imbricate umbilical flange. It differs from G. esnehensis in 

 having a biconvex test, a much lower dorsal side and a more protruding ventral one, 

 quadrangular chambers on the ventral side and less inflated ones on the dorsal, 

 much wider umbilicus and an imbricate umbilical flange. Globotruncana falsostuarti 

 Sigal has a similarly wide umbilicus and discontinuous umbilical flange, but is 

 distinguished by its double keel and more protruding ventral side. 



Globotruncana fareedi sp. nov. was probably confused in the past with both 

 G. rosetta rosetta (Carsey) and G. falsostuarti Sigal. However, G. rosetta rosetta is 

 distinguished by its perfectly plano-convex, umbilico-convex test ; double keel on 

 the early chambers of the last whorl, becoming single on the last chambers ; its flat 

 crescentic chambers on the dorsal side, and angular conical, strongly protruding ones 

 on the ventral ; its narrower umbilicus, and slightly rougher surface. The forms 

 described as G. rosetta (Carsey) by Keller (1946) and as G. rosetta insignis by Gandolfi 

 (1955) are not related to G. rosetta, but probably belong to the present species, 

 although Gandolfi's form shows a flatter dorsal side and a slightly narrower umbilicus. 

 Again, G. falsostuarti Sigal was so briefly described that its diagnostic features were 

 not really known, and thus it has often been misinterpreted. The forms figured by 

 Knipscheer (1956) as G. falsostuarti are different from Sigal's holotype, but may well 

 belong to the present species, while the form described as G. rosetta pembergeri by 

 Papp & Kupper (1953) most probably belongs to G. falsostuarti Sigal. Through the 

 kindness of Dr. J. Sigal, the type specimens of G. falsostuarti, which are in his 

 personal collection, were examined by the present author. This examination 

 showed that : 



1. The holotype of G. falsostuarti is distinguished by its unequally biconvex test ; 

 strongly protruding ventral side ; two closely spaced keels, the ventral one 

 of which is slightly shifted towards the inner side of the test and is reduced 



