300 THE RECAPITULATION THEORY 



preserved as fossils, afford reliable indications of 

 zoological affinity, it is possible to test directly 

 this correspondence between palaeontological and 

 embryological histories, while in some instances a 

 single lucky specimen will afford us, on a particular 

 point, all the evidence we require. 



Great progress has already been made in this 

 direction, and the results obtained are of the most 

 encouraging description. By Alexander Agassiz 

 a detailed comparison was made between the fossil 

 series and the developmental stages of recent forms 

 in the case of the Echinoids, a group peculiarly 

 well adapted for such an investigation. The two 

 records agree remarkably in many respects, more 

 especially in the independent evidence they give as 

 to the origin of the asymmetrical forms from more 

 regular ancestors. The gradually increasing com- 

 pilation in some of the historic series is found to 

 be repeated very closely in the development of 

 their existing representatives; and with regard to 

 the whole group, Agassiz concludes that,* " com- 

 paring the embryonic development with the 

 palaeontological one, we find a remarkable similarity 

 in both, and in a .general way there seems to be a 

 parallelism in the_apearance of the fossil genera 

 and the successive stages of the development of 

 the Echini." Neumayr Tias followed similar lines, 

 and by him, as by other authorities on the group, 

 there seems to be general agreement as to the 



* A. Agassiz, " Palaeontological and Embryological Develop- 

 ment," an Address before the American Association for the 

 Advancement of Science, 1880. 



