SUCCESSION AND STANDING OF ANIMALS. 161 



coincidence with the succession of their representatives in 

 past ages may be entirely overlooked. On that account, 

 it would be presumptuous on my part to pretend that I 

 could illustrate this proposition through the whole animal 

 kingdom, as such an attempt would involve the assertion 

 that I know all these relations ; or that, where there 

 exists a discrepancy between the classification and the 

 succession of animals, the classification must be incorrect, 

 or the relationship of the fossils incorrectly appreciated. 

 I shall, therefore, limit myself here to a general compa- 

 rison, which may, however, be sufficient to show that the 

 improvements which have been introduced into our systems 

 upon purely zoological grounds have nevertheless tended 

 to render more apparent the coincidence between the 

 relative standing among living animals and the order 

 of succession of their representatives in past ages. I have 

 lately attempted to show, that the order of Halcyoiiaria 

 among the Polyps, is superior to that of Actinaria ; l that 

 in this class compound communities constitute a higher 

 degree of development, when contrasted with the cha- 

 racters and mode of existence of single Polyps, as 

 exhibited by the Actinia ; that top-budding is superior to 

 lateral budding ; and that the type of Madrepores, with 

 their top-animal, or at least with a definite and limited 

 number of tentacles, is superior to all other Actinoids. 

 If this be so, the prevalence of Actinoids in older geolo- 

 gical formations, to the exclusion of Halcyonoids, the 

 early prevalence of Astrseoids, and the very late intro- 

 duction of Madrepores, at once exhibits a correspond- 

 ence between the rank of the living Polyps and the 

 representatives of that class in past ages, though we can 



1 For classification of Polyps, see and AQASSIZ, (L.,) Classification of 

 DANA, q. a., p. 44, note 1 ; also Polyps, Proc. Am. Acad. Sc. and 

 S and HAIME, q. a., Arts, 1856, p. Ib7. 



M 



