JR. Bullen Newton — Egyptian Cretaceous Shells. 403 



being of greater length than height, and having an increased 

 diameter. 



Dimensions. 



Largest valve— Height 71 mm. 



Length ... ... ... ... 61 ,, 



Diameter 24 ,, 



Ermarks. — The Egyptian examples consist of two opposite valves, 

 belonging to distinct individuals. They are contained in a grey 

 compact limestone associated w^ith " Beekite," and exactly similar 

 to the matrix bearing a valve of Ostrea Lyonsi and a specimen of 

 0. Villei. 



Horizon. — Turonian. 



Distribution. — Algeria ; Tunis ; and " Sheet 33 " : Coll. Geol. 

 Surv. Egypt (No. 1,044, Box No. 66c). 



EXPLANATION OF PLATE XV. 



Nerinea Eeuuieniana, Orb. 



Turonian of Abu Eoasch. 



Fig. 1. Fragment from near the base, showing obscure ribbing and marginal 



thickening of the whorls. 

 Fig. 2. Upper portion of spire, with its numerous whorls. 



Fig. 3. Vertical section of Fig. 1, exhibiting the plicated structure of columella, 

 Fig. 4. Front aspect of a weathered specimen in the British Museum, presented by 

 W. M. Newton, Esq. [G. 11,485]. 



Ostrea Lyonsi, sp. nov. 

 Turonian, from hills west of Jebel Zait. 

 Fig. 5. External view of lower valve. 

 Fig. 6. Inner view of same. 



Fig. 7. Profile of a natural cast of interior of another specimen, showing the 

 plicated character of the valves. 



Ostrea Thomasi, Peron. 

 Turonian, west of the Gizeh Pyramids. 

 Fig. 8. External view of upper valve. 

 Fig. 9. Internal view of same. 

 Fig. 10. External view of lower valve of another specimen. 



Protocardia biseeiata, Conrad. 

 Turonian, " Sheet 33." 

 Fig. 11. External aspect of a left valve, showing the concentric and postero- radial 

 sculpture. 



EXPLANATION OF PLATE XVI. 



Ostrea Villei, Coquand. 

 Turonian, " Sheet 33." 

 Fig. 1. External view of lower valve. 

 Fig. 2. Internal view of upper valve. 

 Fig. 3. Exterior of Fig. 2. 



Trigoxoarca multidextata, sp. nov. 

 Turonian, "Sheet 33." 

 Fig. 4. External view of a left valve, showing dentition, scars, etc. 



Arctica Barroisi, Coquand. 

 Turonian, " Sheet 33." 

 Fig. 5. External view of a left valve, exliibiting the regular concftitric sculpture of 

 the species. 



(The figures on both plates are drawn natui-al size.) 



