549 
them had compressed by its elastic force the substance of the mine- 
ral around the cavities, as shown by four sectors or quadrants of 
light which it polarises ; and consequently the mineral must have 
been in a soft or plastic state by fusion when it thus yielded to the 
pressure of the included gas. 
2. On the Anatomical Relations of the Surfaces of the Ten- 
torium to the Cerebrum and Cerebellum in Man and the 
lower Mammals. By William Turner, M.B. (Lond.), 
Senior Demonstrator of Anatomy in the University of 
Edinburgh. 
Comparative anatomists have of late directed considerable atten- 
tion to the determination of the relations of the cerebrum and cere- 
bellum. This has been in great measure due to the publication by 
Professor Owen of a system of classification of the Mammalia 
founded on their cerebral characters. The statement made by that 
eminent anatomist, that the posterior, or third, lobe of the cerebrum 
is peculiar and common to the genus Homo, and that equally pecu- 
liar are the “posterior horn of the lateral ventricle” and the 
“hippo-campus minor,” which characterise the hind lobe, has led to 
much discussion. Various anatomists have published descriptions 
and drawings of dissections of the brains of many of the Quadru- 
mana, especially of several of the higher apes. From these dissec- 
tions, as well as from the older observations of Tiedemann and 
Cuvier, it may now be considered as fully proven, that in the Quad- 
rumana the surface of the cerebellum corresponding to the superior 
surface of the human cerebellum is covered by the cerebrum ; that 
posterior lobes, posterior cornua and hippocampi minores, are pos- 
sessed by these animals.* 
In the mammalia lower in the scale than the Quadrumana, it ap- 
pears to be the general opinion of anatomists that the posterior 
cerebral lobes do not exist, and that, from this circumstance, there is 
always a greater or less amount of cerebellum projecting behind the 
* See Professor Huxley, Dr Allen Thomson, Dr Rolleston, and Mr Marshall, 
in vol. i. of “ Natural History Review,” 1861 ; Professors Van der Ivolk and 
Yrolik in January No. for 1862 ; Professor Huxley, “ Proceedings Zoo- 
logical Society,” 1861 ; Mr Flower, “ Proceedings Royal Society of London,” 
20th June 1861, and 9th January 1862. 
