240 TEETIAET VEKTEBRATA OF THE EATtM. 



Zeuglodon isis, Beadnell, MS. 



[Text-fig. 78.] 



1904. Zeuglodon isis, C. W. Andrews, Geol. Mag. [5] vol. i. pp. 214-5. 



1905. „ „ H. J. L. Beadnell, The Topography and Geology o£ the Fayum Province, p. 44 



(Survey Department, Cairo). 



Type Specimen. — Right ramus of mandible, complete as far as the hinder end of 

 the molar series (text-fig. 78) ; Geological Museum, Cairo. 



This is a very large species, the distance from the anterior end of the mandible to 

 the posterior border of the last molar being about 77 cm. against 48 cm. in Z. osiris. 

 It is distinguished from the contemporary Eocetus schweinfiirthi in having the molars 

 and premolars serrated. The full dentition is present in the mandible, and the first 

 premolar is one-rooted. 



Form. 8f Loc. — Birket-el-Qurun beds (Middle Eocene) : west of Birket-el-Qurun. 



The occurrence of large Zeuglodonts in beds beneath the Qasr-el-Sagha series, 

 in which the types of Z. osiris were found, was noticed by Dames* in his account of 

 Schweinfurth's first collection, vt'hich came from the island Geziret-el-Qorn in the lake 

 Birket-el-Qurun : the beds in which this collection was made are placed by Beadnell 

 in the Birket-el-Qurun series. The existence of this large species was afterwards 

 referred to by myself f and by Stromer J. Recently, Dr. E. Fraas has desci-ibed a 

 large Zeuglodont from beds of the same age, and has made it the type of a new genus 

 and species Eocetus schweinfurthi §, stating that in several respects it is more primitive 

 than Zeuglodon and in some respects intermediate between it and Protocetus. The 

 teeth are described as secodont with a reduced inner tubercle, the edges of the crowns 

 not being serrated as in Zeuglodon ; the full dentition is present in the upper jaw. 

 Dr. Fraas also refers to this species the large vertebrae from the same horizon. These, 

 however, he admits are closely similar to those of the larger American Zeuglodonts. 

 A number of these large vertebrae were collected near Dime in 1900 by Mr. Beadnell 

 and myself, and subsequently he obtained near the western end of Birket-el-Qurun a 

 fine mandibular ramus of very large size with the teeth of typically Zeuglodont 

 form. The dental formula is : i. 3, c. 1, pm. 4, m. 3. This animal, from its tooth- 

 structure, cannot be the same as Eocetus schweinfurthi, although of similar size and 

 from about the same horizon. In his notes, Mr. Beadnell referred to this species as 



* Sitzungsb. k. preuss. Akad. Wiss. vol i. (1883) pp. 130-135. 

 t Geol. Mag. [5] vol. i. pp. 214-5. 



i Beitr. Pal. u. Geol. Oesterreich-Ungarns u. d. Orients, vol. xv. (1903) p. 82. 



§ Originally Mesocetus schiueinfuHM fPalapont. Abhandl., n. s , vol. vi. (1904) p. £17), but Mesocetus having 

 been previously employed, the author changed it: to EocHus (Geol. Centralblatt, vol. v. (1904) no. 1048). 



