290 ON THE STRUCTURE OF THE VERTEBRATE SKULL. 



become weary of wading through empty speculations upon 

 " connation ' and "coalescence," "irrelative repetition' and 

 "transposition," the Dei ex machind who are called in to solve 

 every difficulty — the more heartily does one sympathise with 

 the sarcastic vigour with which Cuvier annihilates the products 

 of their exuberant fancy in the notes to the " Ossemens Fos- 

 siles," and the "Histoire Naturelle cles Poissons." Nor is it 

 possible to peruse without admiration the sagacious reason- 

 ings by which he was led to determinations which, in the 

 majority of cases, have been accepted by those who have fol- 

 lowed him. 



Meckel, Kostlin, in his elaborate and valuable special work 

 on the Vertebrate Skull, and Hallmann, in his excellent essay 

 on the Temporal Bone, have built on Cuvier's foundations, 

 applying further and, in some cases, bettering, his determinations 

 of the homologues of particular bones. No one can study these 

 works carefully and retain a doubt that osseous skulls are con- 

 structed upon a uniform plan, though he may, with Cuvier, give 

 but a hesitating and grudging assent to the notion that it is, in 

 some sense, a modified vertebral column. 



III. That criterion of the truth or falsehood of the vertebral 

 theory of the skull, for which the Okenians do not think it 

 necessary to look, and which Cuvier seems to have sought in 

 vain, has been furnished by the investigations of the embry- 

 ologists from the year 1837 to the present time. 



The first step was the discovery of the visceral arches by 

 Beichert ; the second, the demonstration of the mode of develop- 

 ment of the skull, in all classes of the Vertebrata, by the remark- 

 able researches of Batlike, contained in the " Yierter Bericht 

 uber das Naturwissenschaftliche Seminar bei der Universitat zu 

 Konigsberg," which was published in 1839. I will quote Bathke's 

 statement of his conclusions at length, so that we may have the 

 means of fairly comparing his mode of going to work with that 

 of Oken : — 



" The following results, among others, are deducible from the 

 observations which have been detailed : — 



" (1 .) At the earliest period of foetal life the notochord ex- 



