WIV 
INTliODUCTIOX. 
()])lii(lia. 'i'lie Crocodilia, rc'inains of wliicli occur in both the Middle and Upper 
Mocene beds, are of no special interest, the most important point being the occurrence 
of the genus Tomisioma, a further ])roof of the former wider range of this genus, which 
at the i)resent day is r('])resented by a single species found in the rivers of Borneo, 
Sumatra, and Malacca. One of the species now described is interesting, as being 
in seveial features intermediate between Gliarialis and Tomistoma, in this respect 
a])in-oaching the genera Thoracosnnrus and Gavialosuchus, the latter of which, 
however, is regarded by Mr. Lydekker as identical with Tomistoma. 
Among the Chelonia the Athecate group are represented only by a species of 
Psc])]iOj)iiorns, the humerus of which represents the extreme degree of modification 
for jx'lagic life. This form occurs in tlie marine Middle Eocene beds, where it is 
accompanied by remains of another Sea-Turtle, a member of the genus Tlmlnssocheltjs. 
The terrestrial Cryptodira, remains of which are confined to the Fluvio-niarine (Upper 
Eocene) beds, are represented by several very large species of Testndo, Avhich approach 
in size the giant Tortoises of Madagascar, the Mascarene and Galapagos Islands. 
In the presence of a nuchal shield and double gulars, they approach most nearly the 
'bortoises of Aldabra and Madagascar, and may, in fact, be the direct ancestors of 
those species, as well, possibly, as of some of the extinct Indian forms. The 
occurrence of numbers of the shells of such strictly terrestrial forms as these, 
mingled with tree-trunks and bones of mammals, makes it clear that we owe these 
richly fossiliferous deposits to floods sweeping down a great river draining a 
land-area lying immediately to the south or south-west (see Beadnell, ‘ lieport on 
the Ea}u m.p. GO). 
The rieurodira are represented in both the Middle and Upper Eocene beds : two 
genera are at present known, one [Slercogenys) especially remarkable on account of 
the modification of the mandible and ])alate for crushing the food. In the mandible 
the greatly enlarged symphysis is broad and flat; and in correlation with this a 
secondary hard palate is formed by the meeting of the maxilhe and palatines in the 
middle line beneath the nasal passage, so that the internal narcs open far back, behind 
the lev('l of the crushing-surface of the jaws. The other genus of Bleurodirans is 
Podocnemis, remains of which are found both in the Middle and Upper Eocene beds 
of this region. The same genus also occurs in the Lower Eocene of England and 
India, but at the present day is confined to Madagascai- and South America. This 
])eculiar distribution suggests that although those Chclonians may in the tirst instance 
have reached the Ethio])ian continent from the north, probably it was thence that they 
