THE BRAIN OF MACROSCELIDES. 44.5. 
a distinct angle occurs also in Hrinaceus, Talpa, and Perameles. 
So far as the shape of the cerebral hemispheres, and especially 
also that of the floccular lobes of the cerebellum, is concerned, 
the brain more closely resembles that of Perameles than that of 
the Insectivora. At the same time, distinctions of this kind 
have little if any ordinal value. 
The rhinal fissure is incomplete, being intermediate in this 
respect between Hvrinaceus and Perameles. 
The caudal margin of each hemisphere (fig. 1@) consists of 
two limbs of equal length meeting at an angle of slightly more 
than 90°. A large lozenge-shaped space is left between the 
mesial half of each hemisphere and the cerebellum, and*in this 
the pineal body, the whole of the anterior and a considerable 
part of the posterior pair of corpora quadrigemina are exposed. 
Such a complete uncovering of the mid-brain is rare in mammals. 
A much slighter degree of uncovering occurs in the Marsupial 
Dasyurus and some of the smaller Dasyuride. <A similar 
condition occurs in the Insectivore Centetes, but, as Forsyth 
Major has pointed out, it is probably due to secondary 
retrogressive change. 
It is strange to find a similar exposure of the mid-brain in the 
aberrant Galeopithecus *—in a brain possessing deep and well- 
defined calearine, intercalary, suprasylvian, orbital, and pseudo- 
sylvian sulci. It also occurs in most of the Microchiroptera. 
The cerebellum is very simple and closely resembles that of 
Perameles. This is of little systematic importance, because the 
mere wiping-out of some of the cerebellar fissures and the 
elongation of the floccular lobe in EHrinaceus would produce 
the Perameles-type. 
The only features of crucial importance in attempting to 
distinguish the brain of an Insectivore from that of a Polyprotodont 
Marsupial are those of the cerebral commissures aud the hippo- 
campus. The Marsupial has a small dorsal commissure which 
is derived wholly from the fornix, whereas the upper commissure 
of the Insectivore is derived partly from the fornix and partly 
* For some excellent specimens I am indebted to the kindness of Dr. Charles 
Hose of Borneo. The only accounts of this brain, viz., those of Gervais 
(Journal de Zoologie, tome i., 1872) and Leche (Kongl. Sy. Vet.-Akad. Handl. 
Bd. xxi. p. 48, Stockholm, 1886), are far from perfect. I have given fuller 
information concerning this brain in my forthcoming Catalogue of the Collection 
of Brains in the Royal College of Surgeons’ Museum. 
