HUGH MILLER. XXVIL 



since that time the skull has been regarded as a vertebral 

 column." 



This remarkable hypothesis was at first received with en- 

 thusiasm by the naturalists of Germany, and, among others, 

 by Agassiz, who, from grounds not of a geological kind, has 

 more recently rejected it. It has been adopted by our dis- 

 tinguished countryman Professor Owen, and forms the cen- 

 tral idea in his lately published and ingenious work " On the 

 Nature of Limbs." The conclusion at which he arrives, that 

 the fore-limbs of the vertebrata are the ribs of the occipital 

 bone or vertebra set free, and (in all the vertebrata higher 

 in the scale than the ordinary fishes) carried down along the 

 vertebral column by a sort of natural dislocation, is a deduc- 

 tion from the idea that startled Professor Oken in the forest 

 of the Hartz. Whatever support this hypothesis might have 

 expected from Geology has been struck from beneath it by 

 this remarkable chapter of Mr Miller's work ; and though 

 anatomists may for a while maintain it under the influence 

 of so high an authority as Professor Owen, we are much mis- 

 taken if it ever forms a part of the creed of the geologist. 

 Mr Miller, indeed, has, by a most skilful examination of the 

 heads of the earliest vertebrata known to geologists, proved 

 that the hypothesis derives no support from the structure 

 which they exhibit; and Agassiz has even upon general prin- 

 ciples rejected it as untenable. 



Mr Miller's next chapter, on the structure, bulk, and as- 

 pect of the Asterolepis, is, like that which precedes it, the 

 work of a master, evincing the highest powers of observation 

 and analysis. Its size in the larger specimens must have 

 been very great ; and from a comparison of the proportion 

 of the head in the ganoids to the length of the body, which 

 is sometimes as one to five, or one to six, or one to six and 

 a half, or even one to seven, our author concludes that the 

 total length of the specimens in his possession must have been 



