June 21, 1906] 



NA TURE 



177 



south-eastern Asia, or in a lost land between the latter 

 and Africa. 



Next, perhaps, in point of interest is the discovery 

 o! comparatively giant forms nearly related to the 

 modern hyraxes, which are now as isolated as the 

 elephants. Unfortunately, these Eocene hyraxes- — 

 Saghatherium and Megalohyrax — throw little or no 

 light on the ancestry of the group, although serving 

 to show that it was certainly Ethiopian in origin. 

 Whether certain Tertiary Soutli .American ungulates 

 arc related to the group is left by the author an open 

 question. 



Of not less importance are the discoveries and con- 

 clusions with regard to the origin and relationships 

 of that isolated aquatic group of mammals now re- 

 pri'scnted by the manatis and dugongs. On this 

 piiint the author remarks that there seems to be 

 much evidence in favour of the original view of 

 de Blainville that the Sirenia are intimately related 

 to the Proboscidea. 



" In the first place, the occurrence of the most primitive 

 Sirenians with which we are acquainted in the same region 

 as the most generalised proboscidean Moeritherium is in 

 favour of such a view, and this is further supported by 

 the similarity of the brain-structure and, to some extent, 



Fig. 2. — Skeleton oi AysinoWu 



of the pelvis in the earliest-known members of the two 

 groups. Moreover, in the anatomy of the soft-parts of the 

 recent forms there are a number of remarkable points of 

 resemblance. Among these common characters may be 

 noted the possession of : (i) pectoral mammae ; (2) abdominal 

 testes: (3) a bifid ape.x of the heart; (4) bilophodont molars 

 with a tendency to the formation of an additional lobe 

 from the posterior part of the cingulum. The peculiar mode 

 of displacement of the teeth from behind forwards in some 

 members of both groups may perhaps indicate a relation- 

 ship, although in the case of the Sirenia the replacement 

 takes place by means of a succession of similar molars, 

 while in the Proboscidea the molars remain the same 

 numerically, but increase greatly in size and number of 

 transverse ridges." 



These and certain other facts referred to by the 

 author in a later paragraph point very strongly to 

 the conclusion that not only are the Sirenia and the 

 Proboscidea derived from a single ancestral stock, 

 but that the Hyracoidea — and so .Arsinoitherium — are 

 also derivatives from the same stock, which must neces- 

 sarily have been Ethiopian. 



While thus definitely establishing the herbivorous 

 ancestry of the Sirenia, Dr. .Andrews appears to be 

 equally convinced that the Cetacea (as, despite views 

 NO. 19 I 2, VOL. 74] 



to the contrary that h.ivc been expressed, we should 

 naturally expect) are derivatives from a carnivorous 

 ancestral type. On the evidence of specimens ob- 

 tained from another part of Egypt, Dr. E. Fraas, of 

 Stuttgart, has demonstrated the derivation of the 

 whale-like Zeuglodon (Fig. i) from that group of 

 primitive carnivora known as creodonts. Dr. Andrews 

 not only brings forward .'idditional evidence in favour of 

 this most remarkable line of descent, but he is confident 

 — which Prof. Fraas was not — that Zeuglodon itself 

 is an ancestral cetacean, and consequently that 

 whales are the highly modified descendants of creo- 

 donts. It must be admitted, however, that the links 

 between Zeuglodon and typical cetaceans are at pre- 

 sent unknown ; but it may be hoped that these will 

 be eventually brought to light from the deposits of 

 the MoUattam Range. 



Of the other classes of vertebrates represented in 

 the Favum series we can say but little. Reference 

 should, however, be made to the occurrence of a 

 presumed ratite bird, which if rightly identified is 

 the earliest known representative of the group, and 

 suggests the Ethiopian origin of some members at least 

 of the ostrich group in .Africa. Such an ancestry, as the 

 author remarks, would explain the resemblance ex- 

 isting between the true ostriches 

 and the extinct /Epyornis of 

 Madagascar, and might likewise 

 serve to connect the former with 

 the South .American rheas. 



Giant land tortoises are like- 

 wise proved by the Fayum dis- 

 coveries to have occurred in this 

 |iart of the world at a much 

 earlier date, so far as is known, 

 than elsewhere, and it is note- 

 worthy that the extinct Egyptian 

 species are near akin to the 

 recent Mascarene and Malagasy 

 forms. The association of tor- 

 toises belonging to the pleuro- 

 diran section, now confined to the 

 southern hemisphere, is another 

 fact of prime importance, as 

 tending to throw light on the 

 dispersal of that group and the 

 former relations of the southern 

 continents. 

 With regard to the latter point. Dr. .Andrews comes 

 to the conclusion that the new facts fully endorse the 

 theory of a former land connection between .Africa 

 and South America. " Speaking generally, it appears 

 that (i) probably in Jurassic times .Africa and South 

 .America formed a continuous land-mass ; (2) in the 

 Cretaceous period the sea encroached southwards 

 over this land, forming what is now the South .At- 

 lantic. How far this depression had advanced south- 

 wards at the end of the Secondary period is not clear, 

 but it appears certain that the final separation of 

 the two continents did not take place till Eocene 

 times, and that there may have been a chain of 

 islands between the northern part of .Africa and Brazil 

 which persisted even till the Miocene." 



It will thus be apparent that from whatever point 

 of view we regard the Eocene vertebrate fauna of the 

 Fayum — whether from the morphological, the phylo- 

 genetic, or the distributional — it is practically impos- 

 sible to overestimate its extreme importance. When 

 we reflect that what has been discovered can only be 

 the mere fringe of a most extensive Eocene and 

 Upper Cretaceous Ethiopian fauna we shall be in 

 a position to realise what a great part Africa has 

 played in the past as a birthplace and centre of dis- 



