EGYPTIAN TERTIARY VERTEBRATA 679 



regarded as primitive-toothed whales. Remains of the later 

 members of this group are found widely spread over the world 

 in the Eocene beds, occurring in North America, New Zealand, 

 and Europe. It is only quite lately that any light has been 

 thrown on the origin of these animals. Prof. E. Fraas described, 

 from the lower Middle Eocene limestones of the Mokattam Hills, 

 a skull which in all essential respects is that of a Zeuglodon, but 

 at the same time the dentition is that of a Creodont carnivore, 

 none of the peculiar characters of the Zeuglodont teeth being- 

 present. This specimen, to which the name Protocehts was 

 given, proves fairly conclusively that the Zeuglodonts originated 

 from some Creodont ancestor which acquired aquatic habits, and 

 probably this happened on the northern coasts of the Ethiopian 

 continent. From beds of a little later age in the Fayum an 

 animal, almost precisely intermediate between Protocehts and 

 Zeuglodon, has been described under the name Prozeuglodon. In 

 this creature the skull approximates still more closely to that 

 of the true Zeuglodonts, and the teeth have also acquired the 

 serration characteristic of the group, though at the same time 

 some of the premolars and molars have a third inner root, which 

 is lost in the later forms. In the upper beds of the Middle Eocene 

 of the Fayum typical Zeuglodonts, e.g. Z. osiris, occur ; so that 

 in this region we have a complete passage from Protocehts, in 

 which the teeth are those of a Creodont, to Zeuglodon osiris, 

 in which they are typically Zeuglodont — that is, the molars 

 are two-rooted, and have serrated cutting edges. At the same 

 time the narial opening shifts back, and although it is still well 

 in front of the orbits and the nasal bones are long, the change 

 is in the direction of the type of skull found in the early 

 Odontoceti ; and although the relationship of these animals 

 to the Zeuglodonts has frequently been doubted, there seems 

 much to be said in its favour. This question has lately been 

 discussed by Fraas and by Abel. 



Remains of birds are very rare, and with the exception of 

 fragments of the skeleton of a heron-like wader, the only 

 specimen of importance is the distal end of a tibio-tarsus, which 

 is interesting, because it shows that probably a true Ratite 

 {Eremopezus) existed in the Eocene in this region, and may be 

 the ancestral type from which the Struthiones and iEpyornithes 

 sprung — numerous common characters between the two groups 

 having been pointed out by Burckhardt. A relationship with 



