Alfred Russel Wallace 



I have inquired of Sclater and he tells me that he has a 

 considerable distrust of Gould's information on this point, 

 but that he has not himself studied humming-birds. 



In regard to shells, I have always found that dealers have 

 a positive prejudice against intermediate forms, and one of 

 the most philosophical of them, now no more, once confessed 

 to me that it was very much against his trade interest to 

 give an honest opinion that certain varieties were not real 

 species, or that certain forms, made distinct genera by some 

 conchologists, ought not so to rank. Nine-tenths of his cus- 

 tomers, if told that it was not a good genus or good species, 

 would say, '' Then I need not buy it." What they wanted 

 was names, not things. Of course there are genera in which 

 the species are much better defined than in others, but you 

 would explain this, as Darwin and Hooker do, by the greater 

 length of time during which they have existed, or the greater 

 activity of changes, organic and inorganic, which have taken 

 place in the region inhabited by the generic or family type 

 in question. The manufactory of new species has ceased, 

 or nearly so, and in that case I suppose a variety is more 

 likely to be one of the transitional links which has not yet 

 been extinguished than the first step towards a new per- 

 manent race or allied species. . . . 



Your last letter will be of great use to me. I had cited 

 the case of beetles recovering from immersion of hours in 

 alcohol from my own experience, but am glad it strikes you 

 in the same light. McAndrew told me last night that the 

 littoral shells of the Azores being European, or rather 

 African, is in favour of a former continental extension, but 

 I suspect that the floating of seaweed containing their eggs 

 may dispense with the hypothesis of the submersion of 1,200 

 miles of land once intervening. I want naturalists carefully 

 to examine floating seaweed and pumice met with at sea. 

 Tell your correspondents to look out. There should be a 



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