50 JouURNAL OF COMPARATIVE NEUROLOGY. 
It is not without interest to note that the two outstanding 
features of the cerebral hemispheres of the Archzoceti, even if 
their value as indices of kinship be slight, both find their near- 
est parallel in Cetacea. There are no characters of the brain 
of the modern Cetacea which can be regarded as certainly dis- 
tinctive, if we put aside such features as the extreme dwindling 
of the olfactory apparatus, and the enormous development of 
the neopallium. Both must be regarded as late acquisitions, 
not to be expected in an Eocene mammal. Under these cir- 
cumstances these slight points of positive evidence of the rela- 
tionship of the Archeoceti and Cetacea must be allowed some 
value, as reinforcing the testimony of the skeletal parts. 
If we seek to institute closer comparisons between the 
brain of Zeuglodon and of the Odontoceti and Mystacoceti with 
a view to the determination of its relationships, we are not un- 
naturally doomed to disappointment. It might, perhaps, be 
supposed by some anatomists that the absence of an olfactory 
bulb in the Odontoceti might point to a closer affinity of 
Zeuglodon to the Mystacoceti, in which a small olfactory appa- 
ratus is retained. But there is every indication that the ol- 
factory apparatus of the Odontoceti has become aborted quite 
recently. 
Fic. 3.—Ventral aspect of brain of an early feetus of Monedon. Naiural size. 
a. d., locus perforatus (area desert); 4.0., bulbus olfactorius; /.., lobus 
pyriformis. 
Thus in a specimen of the embryonic brain of the Narwhal 
(Monodon), which was given to me some years ago by Professor 
Howes, the remains of the olfactory bulb (fig. 3, 4.0.) are still 
