540 R. BuUen Newton— Egyptian Lower Tertiary Shells. 



Liihodomiis cordatus? Bellardi, "Cat. Foss. Numm. Egitto": Mem. K. 



Ac. Sci. Torino, ser. Ti, vol. xv (1854), p. 193. 

 Mytihis suhobtusus, D'Arcliiac : Desc. Anim. Foss. Numm. Inde, vol. ii 



(1854), p. 268, pi. xxiii, fig. 13. 

 Mytilus (Lithodomus) cordatus, Mayer - Eymar : Viert. Kat. Ges. 

 Ziiricb, vol. xxxvi (1891), p. 174. 



Description. — Testa elongata, cylindracea, arcuata, tumida, Icevi- 

 gata ; umhonibus injiatis, antice injiexis, cordatis, suhspiratis, 

 prominentibus. (Desliayes.) 



This diagnosis of Lamarck's shell is reproduced from Deshayes' 

 work in preference to the original as being rather more 

 complete. The present examples of the species consist of several 

 excellent casts, the valves of which are attached ; some coral 

 structure is retained at the anterior end of the largest specimen, 

 into which the mollusc had burrowed. The species is easily dis- 

 tinguishable from otiier fossil forms by the strongly modioliform 

 and tumid character of the valves, together with the terminal 

 incurved beaks and its generally striking resemblance to Litho- 

 pJiagus cinnamominus, Chemnitz, of recent seas. The Indian species, 

 M. subobtiisus, agrees in all essential details with L. cordatus, and it 

 has therefore been united here, this being in accordance with the 

 views of Professor Mayer-Eymar. 



Dimensions. 



Largest. Smallest. 



Height 40 10mm. 



Length 20 5 ,, 



Diameter 22 6 ,, 



Remarks. — Bellardi appears to have made the first record of this 

 shell from Egypt. 



Horizon. — Lower Eocene (Libyan Series). 



Distribution. — Paris Basin ; Germany; Belgium; Alps; India; 

 Egypt, Abu Zabel (60a) and fifteen kilometres west of Esna 

 (51c). ColL GeoL Surv. Egypt (No. 645, Box No. 60a; No. 240, 

 Box No. 51o). 



EXPLANATION OF PLATE XIX. 

 MiTRA TUKRicuLATA, Schafhantl. 

 Middle Eocene (Mokattam Series) : Minyeh. 

 FiQ. 1. Dorsal view, with typical spire : Foraminifera are seen at the suture. 



HiPPOCHRENES, ep. 



Middle Eocene (Mokattam Series) : Minyeh. 

 Fig. 2. Ventral aspect, showing obscure spiral ornamentation. 

 PoTAMiDES (allied to) pehditus, Bayau. 

 ? Oligocene : Wadi Natrum. 

 Fig. 3. Portion of a small chert-slab with scattered examples of the shells. 

 Fig. 4. Magnified view of a specimen, showing sculpture ( x 4). 

 OsTREA AYioLA, Mayer-Eymar. 

 Lower Eocene (Libyan Series) : about ten kilometres north of Esna. 

 Fig. 5. External view of lower valve ) 

 Fig. 6. „ „ upper valve T^"^^ ^P'^'^^'^^^" 



Fig. 7. Surface magnification of upper valve, showing striations. 

 Fig. 8. Another lower valve, with adherent surface at the summit. 



