185 
In Wotoryctes it will be seen that the “limbic lobe” forms the 
great bulk of the cerebrum, the dorsal limb or hippocampus ex- 
tending almost to the outer margin of the hemisphere, and the 
ventral limb or pyriform extending round the ventral border to 
form the greater part of the lateral wall. Thus as the pallium 
diminishes the two limbs of the falciform lobe approach one an- 
other at the dorsal part of the cerebrum. If the pallium were 
reduced much below that of Motoryctes the hemisphere would be 
practically “limbic lobe.” I have already referred to the fact 
that in reptiles the hippocampus even extends from the mesial on 
to the dorsal surface. If, then, the statement of Meyer (26) that 
“die Rindenabteilung, welche bei den Saugern der inneren 
Kapsel Ursprung giebt, ist bei den Reptilien noch nicht entwick- 
elt” be accepted, it must be admitted that the hemisphere of 
Reptiles is reduced to ‘limbic lobe,” z.e., that the pallium (in the 
sense of Turner) disappears. This is supported by Edinger’s 
statement (10) that a pallium is “added,” and by Brill’s belief 
that the cerebrum of submammalia is wholly olfactory (3). 
The extremely intimate connection of the peripheral olfactory 
apparatus with the cerebrum of lower vertebrates, and even in the 
majority of Mammals, is a very significant fact when contrasted 
with the much slighter connections of the other sensory 
apparatus. 
The olfactory sense has a physiological significance in lower 
Mammals which it is hard to over-estimate. It constitutes, as 
Broca has pointed out (5), the guide and director of the animal 
in the absence of a higher intelligence. In an animal as high in 
the scale of intelligence as the dog it constitutes the main source 
of information in its search for food and in its recognition of the 
other sex. How much more important must the sense of smell 
be in the sightless Votoryctes, with practically no pallium as a 
basis for intellectual operations! In its search for food and in 
its sexual relations—the two pursuits which must constitute 
almost its whole existence—it relies almost solely upon its sense 
of smell, which as a kind of highly specialised and complicated 
reflex guides the animal through life. 
Associated with this extreme physiological importance of the 
sense of smell the olfactory organ presents many unique anatomi- 
cal features. The peripheral part of the olfactory apparatus 
maintains in the highest Mammals a simplicity of structure 
which characterises the whole peripheral sensory apparatus in 
worms, according to Lenhossek and Retzius,—a fact which is pro- 
bably indicative of a very early specialization of function. This 
peripheral apparatus early in development obtains an insertion 
into a diverticulum of the cerebrum itself—into its morphological 
anterior pole. Early in phylogeny this part of the cerebrum, which 
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