100 



PKEI.KTOX OF MAMMALIA. 



of fatty tissue. The Skeleton of Mammals always shows in its 

 conformation a great analogy with that of Man (AMM. PIIYSIOL. 

 616 649). The differences which are remarked amongst the 

 various animals of this class, depend essentially ; First, on the 

 absence of abdominal members in the fish-like Mammalia, such 

 as the Porpoise, and the Whale, which Zoologists have included 

 in the order Cetacca ; Secondly, in the diminution of the 

 number of lingers, and in the absence of the Clavicle, amongst 

 the greater number of those species whose members serve only 

 for walking; -Thirdly, in variations in the number of Vertebne, 

 especially in the dorsal and caudal regions ; Fourthly, in the 

 inequalities in the relative si/es of the same bones. 



81. Conformation of the Ju-tnL The shape of the bony part 

 of the head varies much, according as the face is more or less 

 extended, or the brain-case developed in a greater degree ; and the 

 Mudv of these differences in proportion is not without interest, 

 since, as we have already seen, there exists in general a very direct 

 connection between the degree of intelligence with which an 

 animal is endowed, ai:d Jie relative si// of that portion of its 

 skull which contains the brain. The further we remove from 

 Ma 11, we see the cranium diminish, the jaws and the nasal cavi- 

 ties become more extended : the orbits are directed more and 

 more outwards, and become less and less distinct from the tem- 

 ; and finally the occipital foramen, (the aperture which 



gives a passage to the 

 spinal marrow,) and 

 the two condyles by 

 which the head is 

 connected with the 

 vertebral column, in- 

 stead of being placed. 

 towards the middle 

 of the inferior sur- 



:',''""','" ']' ^ ' Mir-t^Hr^ni''.-''-^" f;U ' f tlu ' cralli ""'- 

 ,i!\: m/. iiifi-rinr in!i.\i,l:iry: n, orbit; i, in- are carried further 

 r, canine- , //m, in -lar-. , r . , , i 



and further back, and 

 tccupving the posterior aspect of it. So that the jaws, 



