Animal Morphology. 115 



flight, swimming, diving, and rapid running, without fear 

 of an upset or capsizing, to use a most expressive term ; 

 the apparatus of the sense of want, or par vagum, acting 

 from a mechanical point of view, as well-stowed ballast, 

 materially aids safe and rapid motion, and aids in giving a 

 right direction to gravity. 



Taking, then, the entire of this membrane as under the 

 guidance of the sense of weight or force, its great object is 

 locomotion ; whether in flight, defence, or prehension, the 

 grand point is one and the same locomotion. 



Its general outline is thus summed up a vertebral 

 portion, three sets of limbs, and three plants, upon which 

 the limbs are placed or fixed, with their complement of 

 voluntary muscles and synovial membranes. 



Let it be granted that the occipital bone is in some 

 measure the counterpart to the sacrum ; that the condyles 

 of the occiput are equal to the sacro-lumbar articulation of 

 the os sacrum ; that the long tube, posteriorly bounded by 

 the spinous ridge of the sacrum, is represented superiorly 

 by the foramen magnum of the occiput ; that the basilar 

 process of the occiput is equal to the anterior portion of the 

 sacrum, and the posterior expanded plane or curve of the 

 occiput, with its roughened transverse ridge's, is equal to the 

 posterior portion of the sacrum, with its spinous and trans- 

 verse ridges then we get to the entire terminus of the series 

 of segmentation, known as vertebrae, with their expanded 

 and modified terminations. 



The plants, or bony attachments at either extremity of 

 the spine, are highly modified homologies of each other, and 

 subserve distinct ends in bone mechanism. The mastoid 

 process, with its serrated articulation with the occiput ; 

 the zygomatic process, and its union with the malar bone, 

 are viewed as so many modifications of the ilium, pubes and 

 ischium, with limbs, fixed and modified to this occipito-pelvic 



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