330 JouRNAL OF COMPARATIVE NEUROLOGY. 
commissure, each olfactory lobe has fiber connection’ with the 
central body, the protocerebral and tritocerebral lobes of the 
same side. 
The optico-olfactory chiasma connects the olfactory lobes 
with the optic lobe and mushroom bodies of the same side and 
with the olfactory lobe of the other side. 
The tritocerébrum corresponds to the oesophageal ganglia 
of the crustacea. 
The anatomical modifications seen in different species are 
determined by the following factors: the kind of food, the per- 
fection of the senses, and the perfection of the psychic facul- 
ties. In forms that feed on solid food the oesophagus is large 
and the oesophageal commissures elongated, but in forms that 
feed on liquid food, the oesophagus is narrow and the oesoph- 
ageal commissures correspondingly short. The size of the sen- 
sory lobes varies with the perfection of the sense organs; but 
the development of the mushroom bodies, fluctuates with the 
psychic activities. 
In the embryo, the three primitive folds develop into five : 
the first and second form the optic lobes ; the third, the proto- 
cerebral lobes, the central and mushroom bodies, the fourth, 
the deutocerebrum, and the fifth the tritocerebrum. 
Brain of Myriopods and Peripatus. Although constructed 
on the same plan, yet the brains of these forms are not so 
highly developed as those of insects. According to SaINntT- 
Remy the brain of Peripatus is rigorously similar to the brain 
of insects and myriopods. From the standpoint of brain struc- 
ture, the insects, the myriopods and onychophores constitute 
a close group. 
Brain of Crustacea. Like the above forms, the brain con- 
sists of a protocerebrum, a deutocerebrum, and a tritocerebrum. 
The protocerebrum is in all respects comparable to the 
protocerebrum of insects; but in many crustacea the optic 
lobes are not fused with the protocerebral lobes. 
The mushroom bodies present the same aspect, the same 
structure and the same fibrous connections as in the insects. 
They are probably not psychic but optic in function. 
