Literary Notices. Vv 
to such diminutive proportions that the brain resembles the reptilian 
type; and in each successive generation the neopallium becomes larger 
or the creature, in self-defence, is compelled to adopt some safe form 
of life. The Aippopotamus and the Sirenia are examples of mammals 
which have not kept pace in the fierce race for neopallial supremacy 
but survive by adopting habits of life which are eminently safe. The 
condition of the human brain represents the other extreme. Here the 
neopallium has attained its maximum development, and its possessor 
has not had to seek refuge either in a retired mode of life or by any 
protective specialisations of structure either for offence or defence, but 
has attained the dominant position in the animal kingdom, whilst re- 
taining much of the generalised structural features of a primitive mam- 
mal. 
This expansion of the neopallium is general and not restricted to 
any localised areas. Thus we cannot say that the greatness of the hu- 
man neopallium is to be wholly attributed to a growth of the frontal or 
of the parietal or of the occipital areas, as various writers have main- 
tained; because all parts exhibit distinct evidences of extension. But 
some regions exhibit the effects of this general expansion more de- 
cisively than others, and many writers have assumed (quite erroneously, 
I believe) that such effects are to be attributed to localised growth. ! 
Thus there are very noteworthy evidences of growth in the region 
around the insula in the human brain, but this is probably for the most 
part an expression of the general extension in a region which lends 
itself to a clear demonstration of any increase. 
In the early mammals the olfactory areas form by far the greater 
part of the cerebral hemisphere, which is not surprising when it is re- 
called that the forebrain is in the primitive brain essentially an append- 
age, so to speak, of the smell-apparatus. When the cerebral hemi- 
sphere comes to occupy such a dominant position in the brain it is per- 
haps not unnatural to find that the sense of smell is the most influential 
and the chief source of information to the animal; or perhaps it would 
be more accurate to say that the olfactory sense, which conveys general 
information to the animal such as no other sense can bring concerning 
its prey (whether near or far, hidden or exposed), is much the most 
serviceable of all the avenues of information to the lowly mammal lead- 
ing a terrestial life and therefore becomes predominant; and its par- 
ticular domain—the forebrain—becomes the ruling portion of the 
nervous system. 
This early predominance of the sense of smell persists in most 
mammals (unless an aquatic mode of life interferes and deposes it: 
compare the Cetacea, Sirenia, and Pinnipedia for example) even though 
a large neopallium develops to receive visual, auditory, tactile, and 
other impressions pouring into the forebrain. In the Anthropoidea 
alone of non-aquatic mammals the olfactory regions undergo an absolute 
1 There is no doubt that localised hypertrophies do occur, but the funda- 
mental distinction of the human brain is the gemera/ expansion of the whole 
neopallium. 
