554 



physis. The hsemal 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 

 hsemapophysis, and repeats the simple homogeneous character of the corresponding elements 

 of the succeeding (mandibular) arch. 



The appendicular element (23) which diverges from the pleurapophysis (-20), contributes to 

 fix and strengthen the palato-maxillary arch by attaching it to the descending process of the 

 parietal centrum (a) : with which, in most mammals, it ultimately coalesces. The other 

 elements of the diverging member of the arch correspond in number and in the point of their 

 divergence with those in birds, chelonians and crocodiles. They are two in number, suc- 

 ceeding each other, and both become seats of that expansive development which is followed 

 by the multiplication of the points of connection ; thus the proximal piece (ze, ' malar bone ') 

 is connected in the hog not only with the hsemapophysis (21) from which it diverges, 

 but likewise with the muco-dermal bone, called 'lacrymal' (72). The distal piece of the 

 appendage (27) expands as it diverges, and fixes the naso-hsemal arch not only to the 

 frontal pleurapophysis (28), but also to the frontal, parietal and occipital neurapophyses and 

 spines : it also affords, in the hog, as in other mammals, an articular surface to the frontal 

 haemapophysis (29). 



The special names which the vertebral elements alluded to in the foregoing description have 

 received, on account of their peculiar modifications and developments in the cranial region of 

 the vertebrate endoskeleton, will be seen by referring to the column of numbers in the 

 TABLE OF SYNONYMS. The teeth in the hsemal arches, modified to form jaws, are those 

 of the deciduous series. 



Purchased. 



3329. The skull of a male Mask-hog (Bus larvatus). 



It differs from that of the ordinary Wild Boar by the more developed paroccipital processes, 

 which project from the upper and lateral borders of the foramen magnum. The frontal region 

 is flatter and the nasal bones broader ; the latter forming a thick rough ridge on each side. 

 The process developed from above the alveolus of the upper tusk is much longer and termi- 

 nates in a thick rough surface. The bony palate extends further back beyond the last molars, 

 which are relatively smaller. The anterior base of the zygomatic arch swells outward. The 

 first upper premolar is separated by a diastema from the second. The tract of enamel on the 

 under surface of the upper tusks is narrower, but more deeply grooved and ribbed. The 

 second premolar is smaller and more simple, as are also the second incisors. One of the 

 anterior premolars is wanting in the upper jaw, and both, together with the right second pre- 

 molar, are wanting in the lower jaw : the last true molar shows its characteristic relative 

 inferiority of size as compared with that in the Sus Scrofa. 



Purchased. 



3330. The skull of a female Mask-hog (Sus larvatus). 



The sexual distinction is shown by the inferior size of the entire cranium as compared with 

 the extent of the molar series, which is nearly the same as in the male ; in the inferior size 

 of the tusks ; in the absence of the lateral ridges from the nasals, and the reduction of the 



