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 mediaeval 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 

 ' valvulse 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 ^ called in anthropotomy, and 

 with prominences corresponding with Tiedemann's and other anthropotomical definitions 



