254 PROFESSOR OWEN ON THE EXTERNAL CHARACTERS 
who knew those great Apes only in their immaturity, with their small milk-teeth and 
precociously developed brain. Accordingly, the anthropoid characters of the Simia 
Satyrus and Simia Troglodytes, as deduced from the facial angle and dentition, are pro- 
portionally exaggerated in the ‘ Régne Animal’’. As growth proceeds, the milk-teeth 
are shed, the jaws expand, the great canines succeed their diminutive representatives, 
the temporal muscles gain a proportional increase of carneous fibres, their bony fulcra 
respond to the call for increased surface of attachment, the sagittal and occipital crests 
begin to rise: but the brain grows no more; its cranial box retains the size it showed 
in immaturity ; it finally becomes masked by the superinduced osseous developments 
in those Apes which attain the largest stature and wield the most formidably armed 
jaws. Yet, under this show of physical force, the brain of both Orang and Chimpanzee 
is still the better and the larger than is that of the little long-armed Ape, which retains 
throughout life so much more of the characters of immaturity, especially in the struc- 
ture of the skull. 
The Siamang and other Gibbons have smaller but longer upper canines, relatively, 
than in the Orangs and Chimpanzees ; the permanent ones more quickly attain their full 
size, and are sooner in their place in the jaws ; consequently the last molar teeth (m 3) 
come last into place, as they do in the Human species. But, if this be interpreted as of 
importance in determining the relative affinity of the longer-armed and shorter-armed 
Apes to Man, it is a character in which, as in their seeming superior cerebral development, 
the Hylobates agree with some much lower Quadrumana with still smaller canines. 
The systematic zoologist, pursuing this most interesting comparison with clear know- 
ledge of the true conditions and significance of a globular cranium and small jaws within 
the Quadrumanous order, first determines, and takes as his compass or guide-point, the 
really distinctive characters of the Human organization. 
In respect to the cerebral test, he looks not so much for the relative size of the brain 
to the body, as for its relative size in the species compared one with another in 
the same natural group. He inquires what quadrumanous animal shows absolutely 
the biggest brain ? what species shows the deepest and most numerous and winding con- 
volutions? in which is the cerebrum largest as compared with the cerebellum? If he 
finds all these characters highest in the Gorilla, he does not permit himself to be 
diverted from the just inference because the great size and surpassing physical power 
attained in that species mask the true data from obvious view. 
The comparative anatomist would look to the cecum and the ischial integument : if he 
found in one subject of his comparisons (Troglodytes) a long ‘‘appendix vermiformis ceci,” 
as in Man, but no “‘callosities,”—in another subject (Hylobates) the ischial callosities, but 
only a short rudiment of the cecal appendix,—he would know which of the two tailless 
Apes was to be placed next ‘‘ the Monkeys with ischial callosities and no vermiform 
appendix,” and which of the two formed the closer link toward Man. He would find 
1 Ed. 1829, pp. 87, 89. 
