46 JOURNAL OF COMPARATIVE NEUROLOGY. 
project, one on each side of the middle line (fig. 1, d@). Each 
of these is 26 mm. in diameter, and is placed so obliquely that 
its surface looks almost directly backward. Shallow but clearly 
defined furrows separate these two bodies from each other and 
from the area c. In the artificial cast there is only a very 
faintly-marked indication of these bodies (fig. 2, @). 
Ata first glance it might seem that they represent the 
whole cerebellum, in which case c would be part of the cere- 
brum! But careful examination of the natural cast renders 
such an interpretation highly improbable, and comparison with 
the artificial cast seems to finally establish the belief that the 
whole of the region marked c forms part of the cerebellum. 
It is extraordinarly difficult to accurately interpret this pe- 
culiar form of cerebellum. A comparison with other primitive 
types of cerebellum’ points to the probability that the lateral 
buttresses of the mass c represent the floccular lobes, and that 
the walnut-like mass (@) represents the cerebellar lobule which 
I have called ‘‘area C” (of. cet., ‘Catalogue,’ p. 201). 7ifieibe 
objected that the lateral buttress-like mass is much too exten- 
sive to be entirely ‘‘floccular,’’ attention may be called to the 
fact that in the large aquatic Sirenia, which have retained an 
exceedingly primitive type of brain, the floccular lobes are 
enormous in comparison with those of other mammals (of. c7z., 
‘Catalogue,’ p. 346). 
It would perhaps be difficult to find elsewhere in the mam- 
malia a greater contrast than that presented by the smooth, 
reptilian-like cerebral hemispheres of these casts and the highly 
complicated, ultra-mammalian neopallium of the recent whales, 
both Odontoceti and Mystacoceti.? And yet, if we inquire 
into the nature of the factors which have molded the form and 
determined the size of the various parts of the brain in Eocene 
times and at the present, the contrast between the brain of 
Zeuglodon and the modern Cetacea loses much of its signific- 
1 Compare, for example (‘Catalogue of the Royal College of Surgeons,’ 2nd 
edition, vol. 2, 1902), Armadillo (p. 211), Tapir (p. 311), Manatee (p. 346). 
2 Vide ‘Catalogue of the Royal College of Surgeons,’ of. ctt., pp. 348—359.- 
