436 Dr. C. W. Andrews — Extinct Egyptian Vertebrates. 



EXPLANATION OF PLATE XVI. 



Fig. 1. — Anthracomya minima (Ludwig), Hind. Eight valve. Natural size, 



10 by 5 mm. — Fig. 2, magnified. 

 3. — ^. :?wiwMwa (Ludwig), Hind. Eight valve. Natural size, 13 by 8 mm. — 



Fig. 4, magnified. 

 5. — A. l(svis, Dawson. Variety. Left valve, magnified. Natural size, 



8 by 6 mm. 

 6. — A. Icevis, Dawson. Eight valve. Natural size, 7 by 5 mm. — Fig. 7, 



8. — Posidonomya suhovata, sp. nov. Left valve. Natural size, 7 by 5 mm. — 



Fig. 9, magnified. 

 10. — P. subovata, nov. Eight valve, magnified. Natural size, 8 by 6 mm. 

 11. — P. subovata, nov. Left valve. Natural size, 4|- by 3 mm. — Fig. 12, 



magnified. 

 13.— P. subovata, nov. Left valve. Natural size (of Fig. 15), 6 by 4^ mm. 

 14. — P. subovata, nov. Left valve, showing the interior ; magnified. Natural 



size, 8^ by 6 mm. This is not the magnified view of Fig. 13. 

 15. — P. subovata, nov. Magnified view of Fig. 13. 

 16. — Anthracomya Valenciensis, Etheridge. Left valve. Natural size, 



7 by 7 mm. — Fig. 17, magnified. 

 18. — Posidonomya concinna, nov. Fragment. Size of the original shell, 



20 by 18 mm. 

 The enlarged Figures are masrnified about three times. 



11. — Prbliminaby Note on some Eecently Discovered Extinct 

 Vertebrates from Egypt. (Part II.) 



By Chas. W. Andrews, D.Sc., F.G.S., British Museum (Nat. Hist.). 



Mammalia {continued). 



Eotherium cegyptiacum, Owen. 



IN the lower beds remains of a Sirenian are very common, and 

 several more or less complete skulls associated with some portions 

 of the skeleton were found. The skull in most respects resembles 

 that of Halitherium. The snout is strongly deflected and bears 

 . a pair of downwardly directed incisor tusks. There are about seven 

 cheek-teeth, resembling in pattern those of Halitherium. The roof 

 of the skull between the temporal fossEe is flat. A cast of the brain- 

 case has been made, and in most respects it resembles that described 

 by Owen ^ as the type of Eotherium agyptiacum, from the Mokattam 

 of Cairo. Since this seems to have come from nearly the same 

 horizon as our specimens, I believe that there is the highest 

 probability that they are referable to this same species, in spite of 

 some differences between the shape of the natural cast described by 

 Owen and that artificially made from one of our specimens. 



The mandible has a sharply deflected symphysis, which is much 

 thickened below, and it appears that teeth occurred along nearly 

 its whole length. The vertebras, scapula, and os innominatum are 

 almost exactly as in Halitherium. It is, in fact, very remarkable 

 that in a form so old as this (possibly Mid-Eocene, see below) 

 there is no trace of a more generalized structure than in the later 

 Halitherium, and we are apparently no nearer the primitive mam- 

 malian stock from which the Sirenians sprang. 



^ Quart. Journ. Geol. Soc, vol. xxxi (1875), p. 100. 



