304 ANATOMY OF VEKTEBEATES. 



homology be equally recognised. The frontal haimapophysis, 

 fig. 189, 29, and the corresponding half of the haemal spine, ib. 32, 

 are connate on each side in all Mammals. The arch, as in other 

 air-breathing Vertebrates, has no diverging appendage. 



The nasal segment, Niv, is chiefly complicated by the confluence 

 of parts of the enormously developed olfactory capsules, 18, and 

 its typical character is further masked by the compression and 

 mutual coalescence of the neurapophyses, 14. The centrum is 

 usually much elongated, as at 13, and soon coalesces with both 

 neurapophyses, u, and with the nasal capsules, 18. The neural 

 spine, 15, is bifid. The pleurapophysis, 20, or proximal element 

 of the h^mal arch of the nasal vertebra has its real character and 

 import almost concealed by the excessive developement of the 

 second element of the arch, 21, which resumes in Mammals all 

 those extensive collateral connections which it presented in the 

 Crocodile ; and to which are sometimes added attachments to the 

 expanded spine of the frontal vertebra, as w^ell as to that of its 

 own segment. The pleurapophysis, however, besides its normal 

 attachment to its centrum, 13, sends up a process to the orbit, in 

 order to effect a junction with its neurapophysis. The haemal 

 spine, 22, is developed in two moieties, which never coalesce 

 together, although, in the higher Apes, and at a very early 

 period in Man, each half coalesces with the hasmapophysis, and 

 repeats the simple homogeneous character of the corresponding 

 elements of the succeeding (mandibular) arch. 



The appendicular element, 24, which diverges from the pleura- 

 pophysis, 20, contributes to fix and strengthen the palato-maxillary 

 arch by attaching it to the descending process of the parietal 

 centrum, 6 : with which, in most Mammals, it ultimately coalesces. 

 The other elements of the diverging member of the arch corre- 

 spond in number and in the point of their divergence with those 

 in Birds, Chelonians, and Crocodiles. They are two in number, 

 succeeding each other, and both become seats of that expansive 

 developement which is followed by the multiplication of the points 

 of connection ; thus the proximal piece, 26, ' malar bone,' is con- 

 nected in the Hog not only with the ha^mapophysis, 21, from 

 which it diverges, but likewise with the muco-dermal bone, 

 called ' lacrymal,' 73. The distal piece of the appendage, 2:, 

 expands as it diverges, and fixes the naso-htemal arch not only to 

 the frontal pleurapophysis, 28, and parietal parapophysis, 8, but 

 also to the frontal, parietal, and, sometimes, occipital neurapo- 

 physes and spines : it also aflbrds, in the Hog, as in other Mam- 

 mals, an articular surface to the frontal ha3mapophysis, 29. 



