LETTER FROM DARWIN. 469 



1850. Olim meminisse juvahit ! and then, 

 my dear and valued and most enlightened 

 friend, we may study once more together the 

 surface of my native rocks for " auld lang 

 syne." . . . 



NT,) 

 1. > 



FROM CHARLES DARWIN. 



Down, Farnborough, Kent, 

 June 15 [1850, probably]. 



My dear Sir, — I have seldom been more 

 deeply gratified than by receiving your most 

 kind present of " Lake Superior." I had 

 heard of it, and had much wished to read it, 

 but I confess it was the very great honor of 

 having in my possession a work with your 

 autograph, as a presentation copy, that has 

 given me such lively and sincere pleasure. I 

 cordially thank you for it. I have begun to 

 read it with uncommon interest, which I see 

 will increase as I go on. 



The Cirrepedia, which you and Dr. Gould 

 were so good as to send me, have proved of 

 great service to me. The sessile species from 

 Massachusetts consist of five species. . . . 

 Of the genus Balanus, on the shores of Brit- 

 ain, we have one species (B. perforata Bru- 

 guiere), which you have not in the United 

 States, in the same way as you exclusively 



