180 I'PI'ER CRETACEOUS-LOWER TERTIARY FORAMINIFERA 



G. triloculinoides, although, as can be seen from his descriptions and figures, they are 

 morphologically similar, occur in the same assemblage and have the same strati- 

 graphical distribution. Moreover Bronnimann (19526 : 16-17) described as G. 

 linaperta Finlay, forms which are actually G. triloculinoides Plummer. Globigerina 

 linaperta is a Middle Eocene form which may be a descendant of G. triloculinoides. 



White (1928) described as G. bulloides d'Orbigny, G. pseudotriloba White, and G. 

 triangularis White, forms which most probably belong to G. triloculinoides Plummer. 



Bolli (19576) studied samples from the same section of Bronnimann (19526) and 

 examined the holotypes of both White (1928) and Bronnimann (19526). He stated 

 that Globigerina finlayi, G. hornibrooki and G. stainforthi were found to be either 

 exceedingly scarce, or not sufficiently differentiated from existing species to warrant 

 separation. He considered G. finlayi Bronnimann a synonym of G. linaperta Finlay, 

 and G. hornibrooki Bronnimann a synonym of G. triangularis White, while he regarded 

 G. stainforthi Bronnimann as close to G. triloculinoides Plummer. However, Bolli's 

 forms described as G. triangularis White and G. linaperta Finlay are, most probably, 

 G. triloculinoides Plummer. 



Loeblich & Tappan (1957a) considered G. stainforthi, G. hornibrooki, G. finlayi, 

 G. triangularis and G. pseudotriloba as synonyms of G. triloculinoides Plummer. This 

 conclusion is here substantiated by the study of a large population of G. triloculinoides 

 from the Paleocene rocks of the Esna-Idfu region, which shows degrees of variation 

 easily covering the various forms previously described under different names in the 

 present synonymy. 



Loeblich & Tappan also considered Globigerina velascoensis var. compressa White 

 as a synonym of G. triloculinoides Plummer, in spite of the fact that Bolli (19576 ; 78) 

 had previously considered this species to belong to the genus Globorotalia where it 

 became a homonym of Globorotalia compressa (Plummer) ; hence he changed its 

 name to Globorotalia tortiva Bolli. However, Loeblich & Tappan stated that Globo- 

 rotalia toriva Bolli is completely different from Globigerina velascoensis var. compressa 

 White. An examination of the holotypes of White and of Bolli is essential to end 

 this conflict. 



Subbotina (1953) described as Globigerina trivialis n.sp. and Globigerina eocaenica 

 Terquem var. eocaenica Terquem, forms which most probably belong to G. triloculi- 

 noides Plummer, as mentioned by Berggren (1962). 



Brotzen & Pozaryska (1961) erected a new genus Subbotina with Globigerina 

 triloculinoides Plummer as type species. However, as stated above, Subbotina is 

 here considered a junior synonym of Globigerina d'Orbigny. 



Hofker (1960^, i) followed by Berggren (1962) suggested certain trends in the 

 evolutionary development of G. triloculinoides. However, as the Lower and Middle 

 Danian are missing in the sections studied it was not possible to follow these trends. 

 Nevertheless, general tendencies towards a reduction in the size of the test and 

 towards an increase in surface reticulation were observed upwards in the section. 



• Hypotype. P.45586. 



Horizon and locality. Figured specimen, from sample No. 38, Gebel Owaina 

 section. 



