ELEMENTAR Y ANA TO MY. 



[LESS. 



respects than any other vertebrae. They may be (as in the 

 Giraffe, and indeed in Ungulata generally) larger than more 

 post-axial ones. On the other hand, they may be excessively 

 reduced mere delicate laminae of bone, as in Porpoises. 

 The free condition of man's cervical vertebrae is normal and 



FIG. 61. SECTION OF MOST PRE-AXIAL VERTEBRAE, AND PART OF SKULL OF 



SILUROID FISH, Bagrus. 

 {From Professor Owen's "Archetype of the Skeleton.' 1 ') 



at, ax, z>3, 7/4, z>5, v&, and v 7 , centra of the seven most pre-axial vertebrae; 

 s, neural spine of second vertebra ; eo, ex-occipital ; bo, basi-occipital ; hy, hyp- 

 apophysial plate extending along on ventral side of vertebral centra. The lateral 

 parts of the first two vertebrae (between eo and s) are united by suture with 

 each other and the skull. 



almost constant in his class. Not quite so, however, for in 

 the true Whales they usually become anchylosed together, so 

 as to form a sort of cervical sacrum. They may, on the 

 contrary, be distinguished as the only free vertebrae except 

 the coccygeal ones, as is the case in Tortoises ; and as in 

 Birds, where the long and very mobile neck has to supply the- 

 place of an arm in supporting a beak which rivals in delicacy 

 of action any hand and fingers known to us, as is manifes't 

 from the wonderful construction of their many kinds of nest. 



That part of each cervical vertebra which is called the 

 body varies as to shape in the way just described in speak- 

 ing of the cervical vertebrae considered as whole and entire 

 bones. 



The pre-axial concavity and post-axial convexity which the 

 bodies exhibit, represent the much more marked concavity 

 and prominence which we find in some Mammals, e.g. the 

 Sheep and Horse. 



In the lowest Mammals (Echidna and Ornithorhynchus) the 

 cervical transverse processes remain as distinct more or less 



