236 TEETIAEY VERTEBRATA OF THE EATtTM. 



therefore intermediate between the horizons of Protocetus atavus and Zeuglodon osiris : 

 as might be expected, it exhibits some interesting transitional characters in the teeth. 

 Another specimen from the same horizon is a large mandible here described as the 

 type of Zeuglodon isis. From the remains of Z. osiris collected by Mr. Beadnell and 

 myself in the Qasr-el-Sagha series it is not possible to add anything of importance to 

 Stromer's detailed descriptions. 



Genus ZEUGLODON, Owen. 



[Lond. & Edinb. Phil. Mag. (3) vol. xiv. (1839) p.'302.J 



Dental formula : — i. ^ ; c. j ; pm. g ; m. 3-373 . Teeth with not more than two roots. 

 Cheek-teeth with a laterally compressed crown — that of the premolars always strongly 

 serrated on both edges, that of the molars serrated on both or only on the posterior 

 edge. 



Zeuglodon osiris, Dames. 

 [Plate XX. figs. 8, 8 A ; text-fig. 77.] 



1894. Zeuglodon osiris, W. Dames, Palseont. Abhandl., n. s., vol. i. p. 204, pis. xxx., xxxi., xxxiv.- 



xxxvi. 

 „ C. W. Andrews, Geol. Mag. [4] vol. viii. p. 437. 

 „ E. Stromer, Sitzungsb. math.-pliys. CI. k. bay. Akad. Wiss. vol. xxxij. 



p. 345. 

 ,, E. Stromer, Zeitschr. deutsoh. geol. G-esell., Protokolle, vol. 55, p. 37. 



G. Elliot Smith, Proc. Boy. Soc. vol. 71, p. 322. 

 „ E. Stromer, Beitr. Pal. u. Geol. Oesterreich-Ungarns u. d. Orients, vol. xv. 

 p. 65, pis. viii.-xi. 

 1904. „ „ E. Fraas, Palgeont. Abhandl., n. s., vol. vi. p. 199. 



Ti/2)e Specimen. — Portions of premaxillas, left ramus of mandible, and some 

 vertebrae, described and figured by Dames, torn. cit. 1894, pp. 191-204, pis. xxx., 

 xxxi., xxxiv.-xxxvi. ; Eoyal Museum of Natviral History, Berlin. 



31 42 



In this species the dental formula is: z. ^ ; c. j ; pm. ^; m. -^. The first premolar 



is one-rooted. Molars crowded together. The supraoccipital surface is narrow and 

 very deeply concave from side to side, owing to the turning backwards of the sides of 

 the prominent lambdoidal crest (see PI. XX. fig. 8). For detailed description of the 

 skull and mandible, see Stromer's memoirs referred to above. 



Form. & Log. — Qasr-el Sagha beds (Middle Eocene) : north of Birket-el-Qurun. 



