TESTUDINID&. 371 
The metacarpal bones are very short, usually broader than long. ‘The whole foot is short 
and heavy, resembling that of an elephant. 
The pelvis is constructed on the plan of that of the Emydide. 
The femur is distinguisht from that of the Emydidz in the union of the two trochanters 
by a ridge which runs nearly on the level of the head of the bone, when the femur is held perpen- 
dicularly. Between this ridge and the head there is a pit of some depth. The metatarsals and 
the phalanges are not so short as the corresponding bones of the forelimb; but they are much 
shorter than those of the Emydidz. There are only 4 digits, the fifth metatarsal being reduced 
toa rudiment. No digit has more than 2 phalanges. 
Little is known regarding the feet of Hadrianus, but we may confidently expect to find only 
2 phalanges in each digit. While the structure of the digits of Stylemys is not certainly deter- 
mined all the known face point to conditions similar to aliose found in the other genera of the 
family. 
The most striking differences between the skulls of the Testudinida and those of the Emy- 
didz are found in the excavation of the roof of the mouth of the members of the former 
family and in the closure of the stapedial notch. The palate rises high above the level of the 
crushing-surfaces of the upper jaws and the vault thus formed is pared back to between the 
quadrates. The skull of Hadrianus is wholly unknown. The skull of Stylemys presents the 
same vaulting as that of Testudo. 
The geographical distribution of the Testudinidz (fg. 14, p. 33) within historical times is a 
most important and interesting question, and it has within recent years provoked much dis- 
cussion. Dr. Albert Gunther (Proc. Linnean Soc. Lond., cx, 1898, p. 26), as an appendix to 
his presidential address on this subject, has given a list of §1 papers which have a bearing on 
the question. The most difficult question to settle j is how the ancestors of the gigantic tortoises 
which once abounded on the Galapagos Islands and on various groups in the Indian Ocean 
reacht those islands. Originally it was assumed that these ancestors were accidental arrivals, 
borne thither by oceanic currents; but in 1891 Dr. George Baur (Amer. Naturalist, xxv, 
pp. 217-229; 307-326) promulgated the theory that these islands were only the volcanic peaks 
of a great tract of land which had at one time connected these islands with one another and 
with the western coast of America. In a number of papers succeeding this announcement he 
defended this theory. For Dr. Baur’s views the reader is referred to his w ritings, a list of which 
was publisht by Dr. W. M. Wheeler in 1899 (Amer. Naturalist, xxx11, pp. 23~30). 
The present writer does not intend to enter upon a full discussion of the question, but he 
records it as his conviction that in general terms Dr. Baur’s position is correct. Probably the 
simplest way to account, on the old theory, for the presence of these tortoises on these remote 
islands is to suppose that, some time in the distant past,a gravid female was borne by currents, 
swimming or floating ona raft of fallen timber; that she landed on one of the islands; and that 
her descendants were in some similar way distributed to the other islands of the group. But 
these Testudinide are probably of all turtles the least adapted for such transportation. In the 
water they would almost certainly drown within a few hours. Nor is it probable that a raft of 
wood would hold together long enough or well enough to carry one of these turtles, wholly incap- 
able of clinging to such objects, the distance of 700 miles. If this almost miracle of transpor- 
tation had Ben accomplisht, it must have been repeated on a smaller scale many times, in 
order to populate the various islands. And all this work must have been accomplisht long ago, 
and long ago have ceast; have been accomplisht long enough ago to permit the evolution of 
a divciiet species on each island, and have ceast long enough : ago that new arrivals should 
not have disturbed this differentiation. It is difhcult to imagine why the distribution of these 
turtles between the various islands should not have contaled. if it had ever been possible. 
Probably the chances for lizards to reach the Galapagos Islands from the American coast 
and from one island to the other are much better than those favoring the turtles. Yet we find 
the same variation among the lizards of the islands that we find among the turtles. Four 
genera are represented on these islands, of which two, Tropidurus and Phyllodactylus, are 
represented on the American coast. Two others, Conolophus and Amblyrhynchus, are peculiat 
to the islands in question. It seems that the opportunities for the accidental transportation of 
lizards are to-day as good as they could ever have been, yet no species are common to the 
American coast and the Galapagos Islands. We would be justified in expecting something 
