46 Reports and Proceedings — 



Geological Society of London. — November 18, 1874. — John 

 Evans, Esq., F.R.S., President, in the Chair. 



1. " On Fossil Evidences of a Sirenian Mammal (Eotherium JEgxjjy- 

 tiacam, Ow.) from the Nummulitic Eocene of the Mokattam Cliffs, 

 near Cairo." By Prof. Owen, F.E.S., F.G.S., etc. 



The specimens described in this paper were obtained by Dr. Grant, 

 of Cairo, in a block of the white limestone of the Cerithian Nummu- 

 litic zone, quarried extensively for building purposes in the Mokattam 

 Cliffs. They consisted of a few fragments of the base of the cranium 

 and a cast of the entire brain with the commencement of the myelon. 

 The author discussed the characters presented by these remains, 

 which he regarded as having belonged to an extinct Sirenian, pro- 

 bably allied to Halitherium, which he proposed to name Eotherium 

 JEgyptiacum. The characters of the brain, as deducible from the 

 cast, were detailed, and shown to be Sirenian. By comparison with 

 the brains of other Sirenia, the author was led to trace a progress 

 in the cerebral characters of the animals of this type, from its first 

 known appearance in the Nummulitic formation of Egypt to the 

 present day. He also inferred, from its presence in the Nummulitic 

 limestone, that this rock had been deposited not far from a shore. 



Discussion. — The President expressed the pleasure with which he had listened 

 to Professor Owen's exhaustive paper, and said that he thought that the final 

 remarks were of very great interest as indicating that there were probably causes 

 for changes of form. The latest species, although perhaps the most highly organ- 

 ized, did not appear to be the most "long-headed." 



Dr. Murie explained the distinctive characters of the four genera of Sirenian 

 Mammals, Manatus, Rhytina, Halicore, and Halitherium, and stated that he re- 

 garded Halitherium as the highest form, seeing that it was a four-limbed type. 

 He remarked that in the young Manatus the brain differs in form from that of the 

 adult, which was a fact to be considered with reference to the data on which Prof. 

 Owen's deductions were founded. 



Mr. Seeley said that he had no doubt the brain was Sirenian, and indicative of a 

 new genus. The existing genera differed from it, in his opinion, in having the 

 Sirenian characters more strongly marked rather than in showing a higher cerebral 

 type. In general form the brain reminded him rather of a Carnivore than of a 

 Sirenian ; and he thought it indicated affinity with a generalized Carnivorous type 

 more than with the living Sirenians. 



Mr. Bauerman stated that the section from which this fossil was obtained is 

 about 6oo feet high, but the quarries referred to by the author were within about 

 ioo feet of the top, in what had been regarded by Dr. Le Neve Foster and himself 

 as a shallow- water deposit. The lower parts of the Cliff are very like the Chalk 

 with flints, except that they contain Nummulites. 



Mr. Charlesworth remarked that the fossil now before the Society was exceed- 

 ingly interesting, as indicating the extension downwards in time of the Sirenian 

 type. He stated that he did not believe that the English Halitherium Canhami 

 was of Miocene age. 



Dr. Leith Adams said that the Maltese Halitherium was truly Miocene. 



Prof. Owen briefly replied, and concluded by hoping that the objections to any 

 of his conclusions, if reported, would be accompanied by their grounds. 



