in the esna-idfu region, nile valley, egypt 247 



Dimensions of described specimen. 

 Maximum diameter = 0-53 mm. 

 Minimum diameter = 0-42 mm. 



Thickness = 0-26 mm. 



Main variation. 



1. Chambers 12-18, arranged in 2^-3 whorls, generally sinistrally coiled (of 750 



specimens picked at random, 56 coiled dextrally). 



2. The last whorl is composed of 5-9 chambers, but 6-7 is most common. 



Remarks. Globorotalia velascoensis velascoensis was first described by Cushman 

 (1925) as Pulvinula velascoensis n.sp. from the Velasco formation of Mexico. Cush- 

 man (1927) erected Globorotalia as a new genus in which he included Pulvinulina 

 velascoensis. Cushman & Bermudez (1949) split the genus Globorotalia into three 

 subgenera, and considered G. velascoensis to belong to the subgenus Truncorotalia. 

 Dalbiez & Glintzboeckel (in Cuvillier et. al., 1955) followed by Said & Kenway (1956) 

 raised Truncorotalia to generic rank, without giving any reason, and considered 

 G. velascoensis to be a Truncorotalia. Bermudez (1961) considered this species to 

 belong to Pseudogloborotalia Haque, which is a poorly defined genus and may be, in 

 part, a junior synonym of Globorotalia Cushman. Hillebrandt (1962) assigned G. 

 velascoensis to the subgenus Truncorotalia, and included G. occlusa Loeblich & Tappan 

 as a subspecies of it. However, as mentioned above, the subgeneric classification of 

 the genus Globorotalia is best avoided as most forms grade imperceptibly into one 

 another and no sharp lines of demarcation can be drawn. Again, although G. 

 occlusa is morphologically rather similar to G. velascoensis, their differences are too 

 great for them to be included in the same species. 



The present study showed that G. velascoensis (Cushman) includes three distinct 

 subspecies, namely : 



Globorotalia velascoensis velascoensis (Cushman). 

 Globorotalia velascoensis caucasica Glaessner. 

 Globorotalia velascoensis parva Rey. 



Subbotina (1936) considered G. aragonensis Nuttall to be a variety of G. velascoensis, 

 and described as G. velascoensis (Cushman) var. aragonensis Nuttall, a form which 

 she later (Subbotina 1953 : 217-218) reconsidered as G. velascoensis (Cushman). 

 Glaessner (1937a) used Subbotina's form as a basis for a new variety which he 

 named G. aragonensis Nuttall var. caucasica. However, this was found to be more 

 closely related to G. velascoensis than to G. aragonensis, and is thus included here as 

 a subspecies of the former, although both Grimsdale (195 1) and Subbotina (1953) 

 considered it to be synonymous with Globorotalia velascoensis velascoensis. 



Finlay (1939a) described as G. crater n.sp. from the Heretaungan stage of New 

 Zealand, a form which was described as " . . . like aragonensis . . . but has only 

 four or five chambers per whorl, a sharp keel, and a practically flat top ", but no 

 figure was given until later (Finlay 1939c). These later figures were described by 

 Hornibrook (1958) as being of specimens from older beds and therefore not typical. 

 However, the figures given by Hornibrook (pi. 1, figs. 3-5) as G. crater Finlay con- 



