410 



If we turn to the higher Vertebrata, we find, as I have stated 

 above, that, at an early period of their embryonic existence, they also 

 present a cartilaginous arch, stretching from the ethmo-presphenoidal 

 cartilage to the auditory capsule, and supporting the mandibular or 

 Meckelian cartilage on the condyle furnished by its inverted crown. 

 The anterior part of the anterior crus of this arch becomes the pala- 

 tine bone, which is therefore truly the homologue of the fishes' pala- 

 tine. The posterior part of it becomes the pterygoid, which therefore 

 is the homologue of the pterygoidien (and transverse ?) of the fish. 



The produced crown of the arch in the higher Vertebrata becomes 

 either the incus, or its equivalent, the quadratum. I therefore 

 entertain no doubt that the jugal is really the homologue of the 

 quadratum of other oviparous Vertebrata. That the tympanal 

 has no relation whatsoever with the bone of the same name in the 

 higher Vertebrata is indubitable ; and I am unable to discover among 

 them any representative of it. It seems to me to be an essentially 

 piscine bone, to be regarded either as a dismemberment of the 

 quadratum or of the pterygoid. It may be termed the "meta- 

 pterygoid." 



Still less do I find among the higher Vertebrata in their adult 

 state, any representative of the posterior division of the suspensor, 

 constituted by the temporal and symplectique. It is quite clear, 

 that the temporal is not, as Cuvier's name would indicate, the 

 homologue of the squamosal. The whole course of its development 

 would negative such an idea, even if we had not a squamosal already ; 

 and I shall therefore henceforward term it, from its function of 

 affording support to both the hyoid and mandibular arches, the hyo- 

 mandibular bone, " os hyomandibulare," while the other bone of 

 this division may well retain the name of symplectic. 



It is commonly supposed that the hyomandibular, symplectic, 

 metapterygoid, and quadrate are all to be regarded as mere sub- 

 divisions of the quadratum of higher Vertebrata. Such a view, how- 

 ever, completely ignores and fails to explain, the connexion of the 

 hyoidean arch with the hyomandibular bone. In no one of the 

 higher Vertebrata does such a connexion ever obtain between any 

 part of the quadratum and the hyoid, which are quite distinct, 

 and attached separately to the walls of the cranium, in even young 

 embryos of the abranchiate Vertebrata. 



