280 PROFESSOR OWEN ON THE EXTERNAL CHARACTERS 
of which they form the head. Troglodytes differs generically, ordinally, and subclassically 
from Homo, which genus forms the sole order (Bimana) of the Archencephala. 
In preparing the present communication for the Zoological Society, and with special 
reference to the primary aim of the Society—the extension of a knowledge of animals 
and of their place in the natural series, I have clothed the results of my observations 
and comparisons in the usual technical language of systematic zoology. 
I am fully conscious, however, of the relative value in biological science of this de- 
partment and aim of the naturalist’s labours, and of the close resemblance of its lan- 
guage to the garb of thought characteristic of the medizval scholastic mind. 
The essential knowledge of which we are in quest rests on the determination of the 
form and structure of the newly acquired animal, the degree in which it resembles 
therein the previously known species, between any two of which it may thus be deter- 
mined to stand, and the way in which it may have come to differ from them. In the 
zoological method of defining such results as may be attainable and have been attained, 
the differences are sought for, weighed, prominently set forth, and technically defined : 
in the homological quest the resemblances receive most attention; and the result of 
their appreciation is commonly, if not inevitably, some speculation, or tendency to 
speculate, on their cause and relations. 
In the Gorilla, as in other latisternal Apes, the homologue of every organ and of 
almost every named part in Human anatomy is present. 
To transmute a Gorilla into a Man the chief steps would be as follows :—In the 
alimentary canal, to develope the mucous membrane of the small intestines into the 
‘valvule conniventes,’ and to alter the proportions as to length of the small and large 
intestines. To abrogate the sexual distinctions of the dental system : to reduce the size 
of the teeth, especially in relation to the head ; to reduce in a greater degree the size of 
the incisors, and still more so that of the canines, especially in the males, so as to bring 
the crowns of all the teeth to the same level, admitting, and being followed by, their 
arrangement in a continuous unbroken series ; to alter the shape of the canines and con- 
tiguous premolars, and to slightly modify that of the crowns of the other grinding teeth. 
In the nervous system, the steps in transmutation would be to abrogate the law of the 
early arrest of the brain’s growth, and to cause it to proceed, especially in the cerebral 
part, with the general growth and development of the frame, though in a slower ratio: 
to add to the number and depth of the cerebral convolutions, and to modify their dis- 
position: to augment the size of the corpus callosum, both absolutely and relatively to 
the cerebellum and medulla oblongata: to expand the cerebrum in all directions, and 
especially backward beyond the cerebellum, so as to define a ‘ posterior’ or ‘ post-cere- 
bellar’ lobe : to extend the chief cerebral cavity, or ‘ lateral ventricle,’ forward beyond 
the corpus striatum into an ‘anterior horn,’ and backward beyond the hippocampus 
major into a ‘ posterior horn,’ answerable to the cavity sb called in anthropotomy, and 
with prominences corresponding with Tiedemann’s and other anthropotomical definitions 
