NERVOUS SYSTEM. VERTEBRATA. 189 



two casts. The brain, however, was much larger than that 

 of any living Marsupial, being about as large as that of a 

 Pig, Hysena, or Entellus Monkey. 



It possessed very large olfactory bulbs lying almost 

 wholly in front of the hemispheres. 



There was a very deep vertical " orbital sulcus," resem- 

 bling in position that of Macropus or Phascolarctus rather 

 than that of Phascolomys. A very deep prorean sulcus ; a 

 deep (single), oblique, pseudosylvian sulcus (such as that 

 labelled B in Phascolomys) ; suprasylvian and lateral sulci 

 resembling those of Phascolomys rather than those of 

 Macropus, and a postlateral sulcus are the most striking 

 features of these hemispheres. 



Gervais, Nouv. Arch, de Mus., t. v. 1869, p. 236. 



ORDER INSECTIVOEA. 

 Family EEINACEID^:. 



D. 230. The left half of the brain of a Hedgehog (Erinaceus 

 europceus), which had been divided by a mesial sagittal 

 section (figs. 63, 64, & 65). 



Also the left half of another Hedgehog's brain, dissected 

 to show the hippocampus in the lateral ventricle. 



Fig. 63. (xli) 



OLF. TUBER. PYR.L, 



This is one of the simplest and most generalised of mam- 

 malian brains. It closely resembles the brain of the Poly- 

 protodont Marsupials (and especially Perameles) in all 

 points except the arrangement of the cerebral commissures 

 and the hippocampus, because the Hedgehog possesses a 

 small corpus callosum and the Marsupials have none in the 

 true sense. The resemblance between the brains of the 



