DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 527 
What for convenience of description I have termed lobules of the antero-, post- 
parietal, angular, and posttemporal gyri on the right face thus notably differ. Moreover 
it becomes a moot point whether in the area in question parts of these so-called lobules 
are not of a verity representatives of “ plis de passage” of the French, “ connecting” or 
‘annectant ” gyri of English authors, as found in man and monkeys. In MM. Leuret 
and Gratiolet’s grouping of mammals according to brain-convolutions, they give the Seal 
a high place, and separate it from the Carnivora by the Edentata, Marsupialia, and 
Ruminantia. But some of the Urside lead towards the Pinnipedia in their gyral 
condition ; so that the series from the smoother, simpler-brained Felide is really less 
interrupted than their arrangement would warrant’. 
g. Interior structures—On removing a horizontal section, about half an inch in 
thickness at deepest, from the upper face of the left hemisphere, the so-called centrum 
ovale minus of Vicq d’Azyr was exposed. The white matter of the brain here presented 
an elongated and transversely narrowed surface, deeply indented externally by the sulci 
and convolutions, and somewhat less so internally by the fold bordering the interhemi- 
spherical fissure. In the preserved brain in which the section above described was 
made, the central substance was not pure white, but of a pale yellow hue, while the 
cortical grey matter had a fawn tinge, shading in some places insensibly into the 
yellowish centre. The darkness of the white matter, though in part due to the brain 
having been soaked in spirit, was not entirely so produced; for in the fresh condition I 
observed that the variation between the central and cortical substance was less marked 
than in a human subject of the Caucasian variety. The layer of grey matter had a 
relative depth of 35 of an inch; and, excepting a limited area, there was little appre- 
ciable deviation between the different regions. 
A second, deeper horizontal slice laid open the lateral ventricle. This cavity, com- 
pared with the size of the brain, is large, and has a very marked fshape. Its total 
length in a straight line is 2-2 inches; but measured curvilinearly, the body of the 
lateral ventricle is 1-1 inch long, the anterior cornu 0-6, and the posterior cornu 0-9 inch. 
As regards the relative position of the extremities of the lateral ventricle to those of the 
hemisphere, the posterior cornu approaches within 0-7 inch of the occipital lobe, the 
anterior cornu 0°8 inch from the anterior end of the frontal lobe. Thus the ventricle 
is situated nearly equidistant between the front and back of the cerebrum. 
The anterior cornu has an obtusely rounded boundary in front, and is a fossa of 
moderate depth. The corpus striatum is smooth-surfaced and slightly convex; it 
measures in the opened ventricle 0°65 inch antero-posteriorly, and 0-4 inch transversely. 
Proceeding from the foramen of Monro, the choroid plexus, as usual, traverses the 
lateral ventricle in an oblique direction, externally and behind dipping into the descend- 
' The most admirable investigation of Prof. Gervais, ‘‘ Mém. sur les Formes Ceréb. propres aux Carniy. Viv. 
et Foss.,” Nouy. Archiy. tom. yi. 1870, is well worthy of reference. Coming late to hand, I could not avail 
myself of its contents as I could have desired. 
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