508 WILLIAM H. F. ADDISON 
occupies the position which in macrosmatic mammals is occupied 
by the large olfactory lobe, and may be here the remnants of the 
atrophied olfactory lobe. 
Stained sections show that the main part of the bulging out 
of Broca’s ‘lobule désert’ is made by the head of the nucleus cau- 
datus which is at this place curved round to the ventral surface 
Fig. 5 Basal view of anterior portions of hemispheres of brains of two other 
dolphins, to show variations in depth of the depressions surrounding the lobule 
désert. In neither are the furrows so marked as in the brain shown in figure 4. 
In A, the furrow frontad of the lobule désert is very shallow, while in B, it shows 
as a distinct depression mesially, but nearly disappears laterally. xX 4. 
of the brain. But the protuberance is covered at its ventral 
surface by two sorts of cortex. Frontally and mesially there is 
a continuation of the typical frontal cortex, but caudally and 
everywhere laterally there is another cortex-like covering. Sepa- 
rating the one from the other are one or two shallow furrows, as 
shown in the figure of section 153 (fig. 11). The gray substance 
of the frontal cortex here shows the same general structure as 
