386 LOUIS AGASSIZ. 



the progressive theory of Geoffroy be true, in 

 his sense, each class of animals ought to be 

 progressive in its organic type. It appears to 

 me that this is not true. Pray tell me your 

 own views on this point. 



(3.) There are " odd fish ' (as we say in 

 jest) in the Old Red Sandstone. Do these so 

 graduate into crustaceans as to form anything 

 like such an organic link that one could, by 

 generation, come naturally from the other ? 

 I should say, no, being instructed by your 

 labors. Again, allowing this, for the sake of 

 argument, are there not much higher types of 

 fish which are contemporaneous with the lower 

 types (if, indeed, they be lower), and do not 

 these nobler fish of the Old Red Sandstone 

 stultify the hypothesis of natural generative 

 development ? 



(4.) Will you give me, in a few general 

 words, your views of the scale occupied by 

 the fish of the Old Red, considered as a nat- 

 ural group ? Are they so rudimentary as to 

 look like abortions or creatures derived from 

 some inferior class, which have not yet by de- 

 velopment reached the higher type of fish ? 

 Again, I should say, no ; but I long for an 

 answer from a great authority like yours, 

 am most anxious for a good general concep- 



