xx PREFACE. 



severally shown all the homologous parts of the human cerebral 

 organ to exist, under modified forms and grades of development, 

 in Quadrumana. But because the presence or absence of the 

 ' ergot,' or ' pes hippocampi minor,' as defined by Tiedemann 

 (see Vol. II. p. 273 of the present Work), had been used as a 

 zoological character, the anatomical world has been deluged, since 

 the date of the last under-cited work, with descriptions and figures 

 of the homologous part in the Orang and other Quadrumana, as a 

 new discovery mainly serviceable as a battery of contradictory 

 affirmations. 



Nevertheless the distinctive characters of the human brain, such 

 as the manifold and complex convolutions of the cerebral hemi- 

 spheres, their extension in advance of the olfactory lobes and 

 farther back than the cerebellum, thereby defining a posterior 

 lobe, with the corresponding ' horn of the lateral ventricle ' and 

 ' hippocampus minor,' are as available to the zoologist in classifi- 

 cation as are the equally peculiar and distinctive characters of 

 the calcaneum, hallux, and other structures of the foot. 



So much, in connection with the ' fifth way ' and application of 

 anatomy, I regret to find myself compelled to state, in order to 

 expose and stigmatise procedures which consist in representing 

 the homological knowledge and opinions of an author by his de- 

 finitions in a purely zoological work, and in suppressing all re- 

 ference to the descriptions and statements in the anatomical 

 writings of the same author, where his actual knowledge and 

 opinions on the nature and homology of parts are given, and 

 where alone they can be expected to be found. 



Somewhat analogous to the course of observation pursued 

 through the animal kingdom, from the lowest to the highest 

 species, is that which traces each organ through the several 

 phases of its development in the same species. 



The right use of sense, in both ways, stores the understanding, 

 empirically, with a series of facts, as the raw material for reasoning 

 up to their principles. But Embryology has this inferiority, that 



