i849.] NOMENCLATURE. 339 



against species-mongers, or rather against their vanity ; it is 

 useful and necessary work which must be done ; but they act 

 as if they had actually made the species, and it was their own 

 property. 



I use Agassiz's nomenclator ; at least two-thirds of the 

 dates in the Cirripedia are grossly wrong. 



I shall do what I can in fossil Cirripedia, and should "be 

 very grateful for specimens ; but I do not believe that species 

 (and hardly genera) can be denned by single valves ; as in 

 every recent species yet examined their forms vary greatly : 

 to describe a species by valves alone, is the same as to de- 

 scribe a crab from small portions of its carapace alone, these 

 portions being highly variable, and not, as in Crustacea, 

 modelled over viscera. I sincerely apologise for the trouble 

 which I have given you, but indeed I will give no more. 



Yours most sincerely, 



C. Darwin. 



P. S. — In conversation I found Owen and Andrew Smith 

 much inclined to throw over the practice of attaching au- 

 thors' names ; I believe if I agitated I could get a large 

 party to join. W. Thompson agreed some way with me, but 

 was not prepared to go nearly as far as I am. 



C. Darwin to Hugh Strickland. 



Down, Feb. TOlli [1849]. 



My dear Strickland, — I have again to thank you cor- 

 dially for your letter. Your remarks shall fructify to some 

 extent, and I will try to be more faithful to rigid virtue and 

 priority ; but as for calling Balanus " Lepas " (which I did 

 not think of), I cannot do it, my pen won't write it — it is im- 

 possible. I have great hopes some of my difficulties will dis- 

 appear, owing to wrong dates in Agassiz, and to my having 

 to run several genera into one, for I have as yet gone, in but 

 few cases, to original sources. With respect to adopting my 



