108 SKULL OF THE CROCODILE. 



shut out of view the same serial relationship of the 

 paroccipitals, as coalesced diapophyses of the occipital 

 vertebra, with the mastoids 8, and the postfrontals, 12, 

 as permanently detached diapophyses of their respective 

 vertebras. All stand out from the sides of the crauium, 

 as transverse processes for muscular attachment ; all are 

 alike autogenous in the turtles ; and all of them, in fishes, 

 offer articular surfaces for the ribs or haemal arches of 

 their respective vertebrae; and these characters are re- 

 tained in the postfrontals as well as in the mastoids of 

 the crocodiles. 



The frontal diapophysis, 12, is wedged between the 

 back part of the spine, 11, and the neurapophysis, 10; 

 its outwardly projecting process extends also backwards, 

 and joins that of the succeeding diapophysis, 8 ; but, not- 

 v/ithstanding the retrogradation of the inferior arch, it 

 still articulates with part of its own pleurapophysial 

 element, 28, which forms the proximal element of that 

 arch. 



There finally remain in the cranium of the crocodile, 

 after the successive detachment of the foregoing arches, 

 the bones terminating the forepart of the skull ; but, not- 

 withstanding the extreme degree of modification to which 

 their extreme position subjects them, we can still trace 

 in their arrangement a correspondence with the vertebrate 

 type. 



A long and slender symmetrical grooved bone, 13, 

 between 24 and 24, like the ossified inferior half of the 

 capsule of the notochord, is continued forwards from the 

 inferior part of the centrum, 9, of the frontal vertebra, and 

 stands in the relation of a centrum to the vertical plates 

 of bone, 14, which expand as they rise into a broad, thick, 

 triangular plate, with an exposed horizontal superior sur- 



