IN THE ESNA-IDFU REGION, NILE VALLEY, EGYPT 179 



1957a Globigerina triloculinoides Plummer ; Loeblich & Tappan : 183, pi. 40, figs, qa-c ; 

 pi. 41, figs, la-c ; pi. 42, figs, xa-c, pi. 43, figs. $a-c, 8a-gc ; pi. 45, figs. 3«-e ; pi. 46, 

 figs. la-c ; pi. 47, figs. 2a-c ; pi. 52, figs. 3-7 ; pi. 56, figs. 8a-c ; pi. 62, figs. -*,a-\c. 



1957 Globigerina triloculinoides Plummer ; Troelsen : 129, pi. 30, figs, ^a-c, ? 3«-c. 



1959 Globigerina triloculinoides Plummer ; Nakkady (pars) : 461, pi. 3, figs. ^a-c. 



i960 Globigerina triloculinoides Plummer ; Olsson : 43, pi. 7, figs. 22—24. 



i960 Globigerina triloculinoides Plummer ; Bolli & Cita : 13-14, pi. 31, figs. la-c. 



xg6og Globigerina triloculinoides Plummer ; Hofker (pars) : 76, figs. 26«-28c,? 2^a-c ; nonfigs. 

 ■zia-c, i^a-c. 



19601 Globigerina triloculinoides Plummer ; Hofker (pars) : 128, pi. 3, figs. 2-4, ? fig. 1. 

 ? 1961 Globigerina triloculinoides Plummer ; Said & Kerdany : 336, pi. I, figs. qa-c. 



1962 Globigerina triloculinoides Plummer, Berggren : 86—88, pi. 14, figs. la— 2b. 



1962 Globigerina triloculinoides Plummer ; Hillebrandt : 119-120, pi. 11, figs. la-c. 



Description. Test medium sized, triglobular, slightly compressed ; dorsal side 

 very slightly raised ; ventral side strongly inflated ; equatorial periphery roughly 

 ovoid, tripartite, distinctly lobate ; axial periphery rounded ; chambers on the dorsal 

 side 11, arranged in 3 dextrally coiled whorls ; the initial chambers are very small, 

 inflated, and increase slowly in size to the beginning of the last whorl, where the 

 chambers increase very rapidly in size ; the last whorl thus constituting most of the 

 test, and the last chamber almost half the test ; the last whorl is composed of 3 J 

 large, subglobular chambers ; on the ventral side the chambers are nearly 3J, 

 globular and strongly inflated ; sutures on the dorsal side short, curved, depressed in 

 the early part, and long, depressed, very slightly curved in the later part ; on the 

 ventral side the sutures are strongly depressed, nearly straight and radial ; umbilicus 

 roughly triangular, narrow, shallow and open ; aperture interiomarginal, umbilical, 

 covered by a distinct, prominent lip ; wall calcareous, thin, finely perforate ; surface 

 coarsely pitted. 



Dimensions of described specimen. 



Maximum diameter = 0-45 mm. 

 Minimum diameter = 0-33 mm. 



Thickness = 0-32 mm. 



Main variation. 



1. Chambers 6-12, arranged in 2-3 whorls, dextrally or sinistrally coiled (out of 



610 specimens studied, 280 coiled sinistrally). 



2. Chambers in the last whorl 3-4, moderately or rapidly increasing in size. 



3. The surface reticulation varies from coarse to moderate. 



4. The apertural flap varies in size, and the aperture in some specimens tends to 



extend very slightly outside the umbilicus. 



Remarks. G. triloculinoides is distinguished by its small, low trochospiral, 

 globular test ; its tripartite appearance ; distinctly pitted surface ; large, inflated 

 chambers of the last whorl ; narrow, shallow umbilicus ; and well-developed apertu- 

 ral flap. This species also exhibits a wide range of variation. Such variation, 

 which obviously falls within the limits of a single species population was used by 

 Bronnimann (1952&) as basis for erecting three new species : G. finlayi, G. horni- 

 brooki and G. stainforthi. He tried to distinguish between each of these forms and 



