490 LOUIS AGASSIZ. 



medusae has already been recognized. I do 

 not here allude to their primitive origin, but 

 simply to the general fact that among radi- 

 ates the embryos of the higher classes repre- 

 sent, in miniature, types of the lower classes, 

 as, for instance, those of the echinoderms re- 

 semble the medusse, those of the medusse the 

 polyps. Having passed the greater part of 

 last winter in Florida, where I was especially 

 occupied in studying the coral reefs, I had the 

 best opportunity in the world for prosecuting 

 my embryological researches upon the stony 

 corals. I detected relations among- them which 



o 



now enable me to determine the classification 

 of these animals according to their mode of 

 development with greater completeness than 

 ever before, and even to assign a superior or 

 inferior rank to their different types, agreeing 

 with their geological succession, as I have 

 already done for the fishes. I am on the 

 road to the same results for the mollusks and 

 the articulates, and can even now say in gen- 

 eral terms, that the most ancient representa- 

 tives of all the families belonging to these 

 great groups, strikingly recall the first phases 

 in the embryonic development of their suc- 

 cessors in more recent formations, and even 

 that the embryos of comparatively recent 



