S52 FOSSILS PROM THE LOWER OLD RED SANDSTONE. 



to his wants and desires : a yet further modification of th» 

 tongue takes place ; the end is attained, and man communi- 

 cates his mind to his fellows. Now, it seems to be on this 

 principle of adapting previously existing parts, with definite 

 iainctions assigned to them, to entirely new uses, that the 

 scapular belt is brought forward, in the ganoids and the ordi- 

 nary fishes, from what is its normal place in the placoids and 

 the higher vertebrata, and made fast to the cranium in the 

 character of an opercular cincture. It serves also in this 

 position to strengthen, by its attachments at the isthmus and 

 super-scapular bones, what would be otherwise, from the great 

 size of the gill-openings, a weak part of the animal. And 

 its original use as a base of the pectorals it continues to 

 serve as fully and adequately in its position of misplacement, 

 as if it had been applied to no other. Such seems to be the 

 simpler reading of the riddle furnished by that ichthyic at- 

 tachment of the scapular belt to the skull, which Nature has 

 adopted in the mechanism of the ganoid fishes. 



THE END. 



Edinburgh : PHnted by M'farlane Ss^ Erskine. 



