110 SKULL OF THE CROCODILE. 



tions, by which they are made subservient to a variety of 

 functions unknown in the haemal arches of the rest of the 

 body. Thus, the two anterior haemal arches of the head 

 perform the office of seizing and bruising the food ; are 

 armed for that purpose Avith teeth: and, whilst one arch 

 is firmly fixed, the other works upon it like the hammer 

 upon the anvil. The elements of the fixed arch, called 

 " maxillary arch," have accordingly undergone the great- 

 est amount of morphological change, in order to adapt 

 that arch to its share in mastication, as \^ell as for forming 

 part of the passage for the respiratory medium, which is 

 perpetually traversing this hasmal canal in its way to 

 purify the blood. Almost the whole of the upper surface 

 of the maxillary arch is firmly united to contiguous parts 

 of the skull by rough or sutural surfaces, and its strength 

 is increased by bony appendages, which diverge from it 

 to abut against other parts of the skull. Comparative 

 anatomy teaches that, of the numerous places of attach- 

 ment, the one which connects the maxillary arch by its 

 element, 20, with the centrum, 13, and the descending 

 plates of the neurapophyses, 11:, of the nasal segment, is 

 the normal or the most constant point of its suspension, 

 the bone, 20, being the pleurapophysial element of the 

 maxillary arch: it is called the "palatine," because the 

 under surface forms a portion of the bony roof of the 

 mouth, called the "palate." It is articulated at its fore 

 part with the bone, 21, in the same plates, which bone is 

 the hsemapophysial element of the maxillary arch : it is 

 called the " maxillary," and is greatly developed both in 

 length and breadth ; it is connected not only with 20 be- 

 hind, and 22 in front, which are parts of the same arch, 

 and with the, diverging appendages of the arch, viz., 26, 

 the malar bone, and 21, the pterygoid, but also with the 



