19s upper cretaceous-lower tertiary foraminifera 



Main variation. 



i. Chambers 12-15, arranged in 2^-3 whorls generally sinistrally coiled (of 510 

 specimens studied, 80 coiled dextrally). 



2. Chambers in the last whorl 4-5 ; 4! is most common, but specimens with 5-6 



chambers also occur and are considered transitional to G. angulata abundo- 

 camerata. The last chamber is in most cases smaller than the penultimate. 



3. The surface may be moderately or strongly roughened, especially on the 



ventral side and along the periphery. 



Remarks. The present subspecies was first described by White (1928) as Globi- 

 gerina angulata. Glaessner (1 937ft) removed it from Globigerina to Globorotalia 

 because of the truncata, angular shape of its chambers. Dalbiez & Glintzboeckel 

 (in Cuvillier et al. 1955) and Hillebrandt (1962) considered this species to belong to 

 Truncorotalia, while Bermudez (1961) considered it to belong to Pseudogloborotalia. 

 Bolli (19576), Loeblich & Tappan (1957a), Olsson (i960) and Bolli & Cita (19606), 

 considered the species to belong to the genus Globorotalia. 



Loeblich & Tappan (1957a) apparently confused G. angulata White with forms 

 which probably belong to Globorotalia occlusa Loeblich & Tappan (see synonymy) . 



Nakkady (1959) described as G. angulata (White) a form which is completely 

 different from White's original description and figures. However, Nakkady & 

 Talaat (in Nakkady 1959) described as Globorotalia quadrata n.sp., a form which is 

 probably G. angulata angulata (White). 



Grimsdale (1951) stated that G. angulata (White) is probably a junior synonym of 

 G. simulatilis (Schwager) 1883, but the two forms appear to be distinct, although very 

 little is known about the holotype of Schwager. 



Globorotalia angulata (White) is distinguished by its very low, trochospirally 

 coiled, umbilico-convex test ; its flat to slightly inflated, imbricate dorsal side, and 

 strongly protruding ventral one ; its angular, truncate, conical chambers, its acute 

 to subacute periphery which has no marginal keel but is covered, in well preserved 

 specimens, with few, stout, spine-like projections which may simulate a keel ; its 

 4-5 chambers in the last whorl which increase rapidly in size ; its curved, depressed, 

 dorsal sutures and radial, strongly incised, ventral ones ; its granular or rather pitted 

 surface ; its very small, deep, open umbilicus, and its long slit-like aperture which 

 extends to the periphery and is covered by a delicate lip in well preserved specimens. 



As mentioned by Bolli (19576) G. angulata angulata (White) probably evolved from 

 G. uncinata uncinata Bolli in early Middle Paleocene time, although its evolution 

 from the more closely related G. quadrata (White) is not excluded. On the other hand 

 it is believed to have evolved in two directions, one leading to G. angulata abundo- 

 camerata Bolli and the other to G. aequa Cushman & Renz. 



Hypotype. P.45595. 



Horizon and locality. Figured specimen, from sample No. 35, Gebel Owaina 

 section. 



Stratigraphical range. Globorotalia angulata was first described by White 

 (1928) from the Velasco formation of Mexico, where he recorded it as " a rare form 



