IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 187 



Turborotalia) on the basis of the presence or absence of keel is not practicable. Species 

 with an acute, non-carinate periphery such as Globorotalia aequa Cushman & Renz, 

 G. angulata angulata (White), G. whitei Weiss, G. wilcoxensis Cushman & Ponton, 

 G. apanthesma Loeblich & Tappan, G. hispidicidaris Loeblich & Tappan, G. pusilla 

 pusilla Bolli and G. uncinata uncinata Bolli neither fit Turborotalia Cushman & 

 Bermudez nor Globorotalia sensu Banner & Blow (1959) and Loeblich & Tappan 

 (1964). 



Thus, in the present study, the genus Globorotalia is considered to include forms 

 with a rounded non-carinate periphery, forms with an acute non-carinate periphery, 

 and others with a marginal keel. The recorded transitional stages between these 

 forms exclude the possibility of splitting the genus into two genera or subgenera, and 

 proves Turborotalia and Truncorotalia to be junior synonyms of Globorotalia. How- 

 ever, while Globotruncana is differentiated from Rtigoglobigerina on the basis of the 

 presence of the keel or keels, no such gradation was recorded between them, although 

 Gandolfi (1955) stated that Globotruncana undergoes a process of globigerinization 

 to evolve into Rtigoglobigerina. Again, the splitting of Hedbergella from Praeglobo- 

 truncana is based only on the presence of a partially or completely developed keel 

 in the latter genus. However, it is not excluded that non-carinate forms have 

 evolved imperceptibly into carinate ones. 



Subbotina (1953) described Acarinina as a new genus distinguished by its Globi- 

 gerina-]ike appearance, which she described as being " well-defined in angular 

 Acarininas and better defined in rounded ones ". She also mentioned that in addi- 

 tion to the angular and rounded Acarininas, "... there are the intermediate species 

 of Acarininas, which are a transitional group between Globotruncana and Acarinina " . 

 In spite of this confusion, her description is identical with that of Cushman & 

 Bermudez (1949) for Turborotalia, which is here considered to be a junior synonym of 

 Globorotalia Cushman 1927, and hence is Acarinina Subbotina. Similarly, Planoro- 

 talia Morozova 1957 ; Rlanor otolites Morozova 1957, Globorotalia (Astrorotalia) 

 Turnovsky 1958, and Globigerina (Eoglobigerina) Morozova 1959 are all junior syno- 

 nyms of Globorotalia Cushman 1927, as their type species conform well with Globoro- 

 talia as defined by Cushman (1927) and emended in the present study. Loeblich & 

 Tappan (1964) considered Globigerina (Eoglobigerina) Morozova to be a junior 

 synonym of Globorotaloides Bolli 1957. The latter genus, as described by Bolli (1957) 

 and emended by Loeblich & Tappan (1964) includes forms transitional between 

 Globigerina and Globorotalia and should be included in part in their synonymy. 

 However, the fact that Bolli mentioned that the ultimate chamber normally has a 

 single aperture, though multiple ones may occur, does not permit its inclusion in the 

 synonymy of either Globorotalia or Globigerina for the time being, although none of 

 his figures showed these multiple apertures. 



Globorotalia is distinguished from Globigerina d'Orbigny by its extraumbilical 

 aperture, the occasional flattening of its chambers, and the occasional presence of a 

 marginal keel and an umbilical everted collar or shoulder. It is distinguished from 

 Rtigoglobigerina Bronniman by the above-mentioned characters, as well as by the 

 lack of an umbilical cover-plate and of surface meridional costae. It differs from 



