PECULIAR TO MAN. 131 



lows the front legs to come near together, to fall perpendi- 

 cularly under the front of the trunk, and support it with 

 firmness and faciUty. Their sternum is long and narrow, 

 the ribs advance nearer to the crista of the os innominatum, 

 and together with the sternum cover a larger share of the 

 abdomen, and support its viscera more eflfectually in the 

 horizontal position of the trunk. For the same purpose too, 

 the ribs in many cases are more numerous than in man, 

 viz. thirty-two in the hyena, thirty-six in the horse, forty in 

 the elephant, and forty-six in the unau (Bradypus didactylus). 

 These, with other points, which cannot escape observa- 

 tion wlien the skeleton of any rather long-legged quadru- 

 ped is compared to that of man, shew how unfit he is for 

 the attitude on all-fours, which in his case can never be 

 otherwise than unsteady, irksome, and fatiguing in the 

 highest degree. 



The spine of man presents some important peculiarities 

 resulting from his characteristic attitude. One of these is, 

 its very remarkable increase of size in the lumbar region ; 

 an augmentation corresponding to that of the superincum- 

 bent w^eight, and to the magnitude of the efforts which this 

 part has to sustain. The immense bulk of the sacrum *, 

 far exceeding, in proportion to the rest of the body, that of 

 any animal, is referable to the same cause, to the mode in 

 which this weight is transmitted to the hip-bones, and 

 thence to the lower limbs, and to the peculiar construction 

 of the pelvis. The waving line f of the column, arising 

 from a series of alternate curves in opposite directions, is 

 altogether peculiar to man ; it allows a proper distribution 

 of the weight with respect to the centre of gravity, the line 



* In the chimpansc^, says Tyson, '' the os sacrum was nothing so dilated 

 and spread, as it is in man ; but contracted and narrow, as it is in apes ; and 

 very remarkably different from the human skeleton." p. 69. 



+ This is excellently represented in Alrinus's plates of the skeleton ; par- 

 ticularly in the side view, tab. iii. I refer to the original Leyden edition of 

 this incomparable work ; which, when the plates of the bones are added, con- 

 stitutes the most accurate, useful, and splendid publication ever produced in 

 anatomy. Its merits cannot be estimated from the English editions. 



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