NERVOUS SYSTEM. - VERTEBRATA. 349 



Quadruped or in the Human subject ; neither is the medulla 

 oblongata so prominent, but flat, lying in a hollow made by the 

 two lobes of the cerebellum. 



" The brain is composed of cortical and medullary substances, 

 very distinctly marked ; the cortical being, in colour, like the 

 tubular substance of a kidney ; the medullary very white. These 

 substances are nearly in the same proportion as in the Human 

 brain. The two lateral ventricles are large, and in those that 

 have olfactory nerves are not continued into them as in many 

 Quadrupeds ; nor do they wind so much outwards as in the 

 Human subject, but pass close round the posterior ends of the 

 thalami nervorum opticorum. The tlialami themselves are large; 

 the corpora striata small ; the crura of the fornix are continued 

 around the windings of the ventricles, much as in the Human 

 subject. The plexus choroides is attached to a strong membrane, 

 which covers the thalami nervorum opticorum, and passes through 

 the whole course of the ventricle, much as in the Human subject. 



" The substance of the brain is more visibly fibrous [specimens 

 D. 527 and D. 528 were prepared by Hunter to demonstrate this] 

 than I ever saw it in any other animal, the fibres passing from the 

 ventricle, as from a centre, to the circumference, which fibrous 

 texture is also continued through the cortical substance. The 

 whole brain in the Piked Whale [Balcenoptera acuto-rostrata] 

 weighed four pounds ten ounces. 



The nerves going out from the brain, I believe, are similar 

 to those of the Quadruped, except in the want of olfactory nerves 

 in the genus of the Porpoise.'' John Hunter, on Whales, Phil. 

 Trans. 1787, p. 423. 0. C. 1838. 



flunterian. 



D. 512. The brain of a Porpoise (Phoccena phoccend) , 



0. 0. 1333 A. 



D. 513. A cast o the cranial cavity of a Porpoise (Phoccena 

 phoccena) . 



The large brain of the Porpoise is one o the smallest in 

 the Cetacean Order, in which the organ attains to a much 

 greater absolute size than in any other animals. In a 

 record by Flatau and Jacobsohn the brain of a Porpoise 

 weighed 468 grammes, being ^gth the total body-weight. 

 Haswell has recorded a lesser brain-weight in this Order, 

 that of Kogia grai/i, which was 454 grammes. 



