IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 169 



istic of G. daubjergensis. Transitional stages between these species are recorded in 

 the present study, and both their morphological features and stratigraphical ranges 

 strongly support this hypothesis. 



Brotzen & Pozaryska, in their original description of the species, recorded a wide 

 range of variation, which included specimens with typical Globigerina characteristics, 

 and others with small, accessory, sutural apertures and/or an additional chamber 

 covering the umbilicus. These forms conform well with the three stages suggested 

 by Hofker (io,6og, i) in the development of G. daubjergensis Bronnimann which he had 

 described as the Globigerina, the Globigerinoides, and the Catapsydrax stages respec- 

 tively. However, as none of these stages was recorded by Bronnimann in his 

 original description, it is possible that Hofkers " Globigerinoides and Catapsydrax 

 stages " are actually the early representatives of G. kozlowskii. 



These various, distinct stages in the same species population, recorded by Brotzen 

 & Pozaryska, made it difficult to decide with certainty the taxonomic position of 

 the species. However, these authors considered the wall structure of the test to be 

 the main criterion for classification, and as G. kozlowskii was said to have the same 

 wall structure as typical Globigerina, it was considered to belong to Globigerina s.L, 

 in spite of the accessory sutural apertures and the umbilical bulla. 



The form here described as G. kozloskii is a typical Globigerina as it has neither the 

 accessory sutural apertures, nor the umbilical bulla. However, these minute sutural 

 apertures were observed in a few specimens in the same population. Until further 

 study of populations of both G. kozlowskii and G. daubjergensis in their type areas 

 explains why these species apparently show the characters of more than one genus, 

 the present species is considered to belong to the genus Globigerina. It should be 

 noted that the holotype of G. kozlowskii was clearly shown to have accessory sutural 

 apertures. Retention of the species in Globigerina is further justified by the fact 

 that these accessory apertures appear to be different from those of typical Globi- 

 gerinoides species, and are only very feebly represented in the specimens from the 

 Esna-Idfu region and in topotype material kindly sent to the author by Dr. K. 

 Pozaryska. Forms with an additional chamber covering the umbilicus (umbilical 

 bulla) were not encountered in the samples studied, and were only recorded as rare 

 in the type area. 



G. kozlowskii is possibly related to the similar, highly trochospirally coiled, 

 Paleocene forms such as G. chascanona Loeblich & Tappan, G. aquiensis Loeblich & 

 Tappan, and G. spiralis Bolli. 



Gartner & Hay (1962) considered G. kozlowskii to be a junior synonym of G. 

 aquiensis Loeblich & Tappan, although the latter is clearly distinguished by its 

 roughly quadrangular chambers which increase slowly in size and are slightly 

 elongated in the direction of coiling, and by its wider umbilicus and spinose surface. 



Hypotype. P. 45579. 



Horizon and locality. Figured specimen, from sample No. 7 Gebel El- 

 Kilabiya section. 



Stratigraphical range. The species was first described from the Paleocene of 

 the " Pamietowo " well of northern Poland. Brotzen & Pozaryska (1961 : 156) 



