THE THEORY OF THE VERTEBRATE SKULL. 295 



perhaps the quadrate bones of many other Vertebrata in a part 

 of them. Around them, however, is developed, in animals 

 provided with an osseous skeleton, a coating of bony plates, 

 which becomes metamorphosed into the lower jaw. 



" At the outer side of those parts, moreover, in which the 

 pterygoid and palatine bones arise — or, in other words, along- 

 side the processes of the ' rays ' — a substance arises, whence the 

 upper maxilla and the malar bone are developed. 



" The upper maxilla and malar bone therefore might be 

 regarded, like the lower maxilla, as splint bones or rib-like 

 bones (which, however, do not occur in connection with true 

 ribs), but not as parts of the vertebra itself.* The lachrymal 

 bone, lastly, only fills up a gap between other bones of the face, 

 and therefore, if analogies must be discovered, can only be 

 regarded as an intercalary bone. 



" (12.) The auditory capsules and the petrosal bones, which 

 are developed out of them in many animals, may, in respect 

 of their place and origin, be most fittingly compared with those 

 intercalary bones which occur in Sharks and Sturgeons, between 

 the arches of the vertebra? ; but, in respect of their form, take a 

 different course from these. And since those intercalary pieces 

 can hardly be considered to be parts of vertebrae, the auditory 

 capsules cannot be regarded as such." 



Vogt and Agassiz, resting upon embryological observations 

 which entirely confirmed those of Rathke, carry out the argu- 

 ment suggested by the latter more rigorously. 



" It has therefore become my distinct persuasion (says Vogt) 

 that the occipital vertebra is indeed a true vertebra, but that 

 everything which lies before it is not fashioned upon the verte- 

 brate type at all, and that all efforts to interpret it in such 

 a way are vain ; that therefore, if we except that vertebra 

 (occipital) which ends the spinal column anteriorly, there are no 

 cranial vertebrae at all." f 



* In the Chelonia and a few Mammalia bony elements occur, which cover the 

 ribs and, in the first-mentioned animals, even become united with the ribs ; they are 

 developed, however, in the integument, and belong to the integumentary skeleton, 

 and not to the nervous skeleten, so that they need not be considered here. 



f " Entwickelungs-Geschichte dor GeburtsheliVr Krote."— P. 100. 1842. 



