586 TRANSACTIONS OF SECTION H. 
New World Platyrrhines, in association with others that seem to suggest a very 
early Anthropoid, the Propliopithecus Haeckelii (Schlosser), is a most suggestive 
discovery. It accords, however, with the scheme of Primate evolution and 
migrations which is based upon the other evidence at our disposal; so that some 
such hypothesis as I shall now sketch naturally shapes itself in our minds. 
As the Tarsioids entirely disappeared from North America by the Middle 
Eocene and are not known to occur anywhere else in the world, either in past or 
present times, except as.the Spectral Tarsier of the South-eastern corner of Asia, 
we must assume that some Tarsioids took refuge in Asia, which they reached, 
if they were not there before, by Scharff’s hypothetical trans-Pacific land-bridge 
in the Early Eocene, before their brethren disappeared from North America. 
But it seems probable that some of the Tarsioids that lived in North America 
in Early Eocene times became transformed from Prosimiz into true monkeys of 
a very primitive Platyrrhine type, distinguished, among other things, from their 
Lemuroid ancestors by a much higher development of the power of skilled move- 
ment, of which tangible evidence is forthcoming in the considerably larger and 
more highly specialised motor area of their modern descendants.*? 
The true monkey seizes its food with its hands, and not with its jaws, as the 
Lemur does. 
A noteworthy increase occurred also in the visual cortex, and especially in 
those outlying parts of it which do not receive impressions directly from the 
optic tracts, but presumably are concerned with the storing of visual memories 
and associating them with tactile and acoustic impressions. 
There is a corresponding, and perhaps relatively greater, change in the 
auditory centres. 
Although the fossil beds of America have not yet yielded up the intermediate 
stages in these transformations, we have in the Middle Eocene Notharctids, those 
curiously half-formed Platyrrhines, and others of their contemporaries,** some 
evidence of the experiments Nature was performing in the process of creating 
Apes. And if it be objected that it is mere conjecture to say that the Tarsioids 
which went southwards in America were transformed into Platyrrhine monkeys 
by the time they reached Patagonia, it must be remembered that the vast 
continent which formed the link between California and Patagonia in those days, 
if we follow Scharff,*4 is now submerged, with all its relics of the birth and 
early history of the Apes. It is highly probable that some of the primitive Platyr- 
rhines which were thus evolved spread from America into the Old World. . Those 
that remained in the former continent spread south, leaving North America 
entirely without Primates; and in the relative seclusion of the South American 
forests they retained much of their primitive structure, but some of them sacri- 
ficed part of the advantage, from the point of view of mental evolution, gained 
when they took the upward step from the Prosimian to the Simian status, by 
devoting the special skill they had acquired to developing the prehensile powers 
of their tails, rather than concentrating such potentialities in the more serviceable 
culture of their hands. 
Their brethren who crossed into the Old World took the higher course, and 
eventually achieved the greater distinction, when they became especially expert 
in performing the most delicate movements with their hands. 
Which of two land-bridges, trans-Pacific and trans-Atlantic, available in the 
Karly Tertiary Age from Central America to Asia and Europe respectively,** 
the primitive monkeys traversed there is no definite evidence to indicate. For, 
while most writers assume that they went directly from North America to 
Western Asia, it must be borne in mind that the earliest remains of monkeys in 
the Old World occur in Egypt and Europe; and thus it is not altogether im- 
probable that the Platyrrhine ancestors of the Catarrhines set out on their 
journey to the Old World by the trans-Atlantic route, and perhaps underwent 
the earlier stages of their further development in North Africa. For in the 
** C. and O. Vogt, op. cit., p. 394. 
*“H. ¥. Osborn, Zhe Age of Mammals, p. 161; also Bull. Amer. Mus. Nat. 
Hist., vol. xvi., 1902; Workman, Amer, Journ, Sei., vol. xv., 1903; and Max 
Weber, Sauaectidre, 1904, p. 763, 
** Scharff, on. cit., fig. 14, 
*5 Thid, 
