ORDINAL TYPES OF MOLARS: CETACKA 



191 



ZEUGLODONTIA. 



The derivation of the serrated cutting molars of Zeuylodon from a 

 more normal type retaining vestiges of the ancient inner portion of the 

 crown, is demonstrated by recent discoveries in Egypt (Figs. 193, 194) 



FIG. 193. Inferior surface of the skull of Prolocttus atavus, from the Lower Middle Eocene of 

 Mokattam, near Cairo, Egypt ; a very primitive Zeuglodont, thought by Prof. Fraas to represent 

 an aquatic offshoot of the Creodonta. The cheek teeth while elongate anteroposteriorly retain 

 vestiges of the internal protocone and of its root. Aquatic adaptation is also indicated in the 

 elongation of the snout, the prehensile modification of the anterior teeth, the secondary bridging 

 over of the posterior nares, the enlargement of the auditory bullaj. About i. After Fraas. 













FIG. 194. Restoration of tha skull of Ziuglodon osiris, from the Middle Eocene of Egypt, 

 showing a further advance of the specialization noted under Fig. 193. Much reduced. After 

 Stromer von Reichenbach. 



