PRESIDENTIAL ADDRESS. 97 



of Europe. The first period might fitly bear the name of its in- 

 augurator, Thomas Say. It is characterized by a rapid advance 

 in the determination of the fauna, the classification of the species, 

 and the exploration of vast areas. It extended from 1817 to 

 1841. 



The second period should bear the name of Dr. A. A. Gould. 

 It was inaugurated by his report on the Invertebrata of Massa 

 chusetts, and characterized by the broader scope of investigation, 

 the interest in geographical distribution, the anatomy of the 

 soft parts, and the more precise definition and exact discrimination 

 of specific forms, as exemplified in his writings. 



The third period would be appropriately called after Dr. Wil 

 liam Stimpson, who eagerly adopted the radical changes in classi 

 fication rendered necessary by the discoveries of Loven, and 

 stood ready to welcome the theory of evolution with all the light 

 it shed in dark places. 



Though violently opposed to evolution, the teachings of Agas- 

 siz did much to hasten the fruition of the new school of students. 

 For the rational methods of teaching and investigation which he 

 devised or made popular, the present era is greatly in his debt. 

 This period can hardly be said to have been introduced by any 

 epoch-making work, but gradually the old methods were discarded 

 for the new. 



The latter were fully exemplified by such works as Morse's 

 u Pulmonifera of Maine" (1864), Stimpson's " Hyd^obiina3 " 

 (1865), and a long list of subsequent publications. 



Of men belonging to the Sayian period may be mentioned Say, 

 Lesueur, Barnes, Green, Morton, Couthouy, Warren, Anthony, 

 Nuttall, Haldeman, and Conrad. 



Rafinesque "vrttsui generis ^ and Lea links this period with the 

 next. 



Of the Gouldian period are Gould, Amos Binney, C. B. 

 Adams, Carpenter. 



