162 ALEXANDER AGASSIZ 



when fully expanded. The Chinamen used to get them 

 very often, of all sizes, in their nets and then cut them 

 up and sell them to unsuspecting Frenchmen who mis- 

 took the species for frogs' legs. Now if Ralston has left 

 any Chinamen in San Francisco, can you speak to a 

 promising specimen of Mongolian and ask him to cling 

 to a good specimen, if the species does not freeze to 

 him. Then by a judicious cutting open of his lower side, 

 so as to let alcohol into his insides, put him into a keg 

 of alcohol and ship him, via Panama, to your humble 

 servant, who will receive him with open arms. 



Should you be in want of any beast from this side, 

 call on me. I hope one of these days to get over to San 

 Francisco and renew my pleasant associations of old 

 days. 



In August, 1880, Agassiz delivered an address before 

 the American Association for the Advancement of Sci- 

 ence, using his knowledge of the Echini to show the 

 extreme difficulty, if not impossibility, of ever obtaining 

 a complete record of the development of even a single 

 group. In acknowledging the receipt of a reprint, 

 Darwin writes : — 



" I read your address with much interest. However 

 true your remarks on the genealogies of the several 

 groups may be, I hope and believe that you have over- 

 estimated the difficulties to be encountered in the future. 

 A few days after reading your address I interpreted to 

 myself your remarks on one point (I hope in some 

 degree correctly) in the following fashion : — 



" ' Any character of an ancient generation or inter- 

 mediate form may, and often does reappear in its de- 



