302 ON THE STRUCTURE OF THE VERTEBRATE SKULL. 



of the structure of the completely ossified brain-case is, I believe, 

 the best that has yet been given. Nay, we may go further with 

 him, and look on the periotic bones as no part of the proper 

 cranial wall, but as special developments within the otic capsule. 

 But here we must stop, for neither anatomy nor development 

 are reconcilable with the notions of the Okenian school respect- 

 ing the limbs of the head. Carus suggested, from the Okenian 

 point of view, that the premaxillse and maxillae must be cephalic 

 ribs, and not cephalic limbs ; but Eathke was the first to 

 demonstrate that the inferior arches of the skull must be con- 

 sidered, if they are homologous with anything in the trunk, to 

 partake of the nature of ribs rather than of that of limbs. But 

 the confusion between analogy and affinity has led to such 

 grave errors in the interpretation of the upper arches of the 

 skull, that we must be upon our guard against running into 

 similar mistakes with respect to the lower arches.- 



It is easy enough to enumerate four inferior arches to the 

 skull, just as there are four superior arches — the premaxillae 

 forming the first of these arches ; the palato-pterygoid and 

 maxillary apparatus, the second ; the mandible, with its sus- 

 pensorium, the third ; the hyoiclean arch, the fourth : and it 

 might be plausibly enough reiDiesented that the first of these is 

 united with the nasal segment of the skull, the second with the 

 frontal segment ; while the third and fourth, being connected 

 respectively with the anterior and the posterior parts of the 

 periotic capsule, might be fairly considered to belong to the 

 parietal and occipital segments. 



But do they really belong to those segments ? and if so, 

 why do they not remain attached to them ? What relation 

 have the branchial arches to the skull, again ? It is hard to 

 see in what morphological character the first branchial arch of 

 a fish differs from its hyoidean arch ; and if so, is it an arch of 

 the skull, or an arch of the vertebral column ? What, further- 

 more, are the original connections of the palato-pterygoid arch ? 

 Does it grow out of the mandibular arch from behind forwards, 

 as Bathke seems to think ; or has it, primitively, that connection 

 with the prefrontal region which is so constant a character of 

 the palatine bone ? 



