TO A. HANCOCK, ESQ. 259 



basis). It is the B. sulcatus of Bruguiere = Lepas balanus, Linn.* 

 You sent me formerly specimens mingled with another species 

 attached to a Pecten with the Clitias. 



Do you know the latitude on the coast of Greenland ? It 

 would be valuable information for me.^ If you do even approxi- 

 matively, will you write it on slip of paper, without anything 

 further, and send it me ? I have this species from Iceland. 



"With respect to Lithotrya, I feel a conviction that if you had 

 seen all the specimens which I have, you would not doubt that 

 all the species bore, in whatever manner this may be effected. 



Yours very sincerely, 



C. Darwin. 



No. 6. 

 (No postal date.) 



Down Farnborough, Kent, 



May 12th. 

 My dear Sir, 



Owing to a perhaps foolish habit of not reading 



periodicals when they come out, I have only just read your very 



interesting paper on the boring of MoUusca in the Annals ; and 



this reminded me that you wished for more information regarding 



Lithotrya. I really do not know what to give. I have three 



specimens of Lithotrya, and I enclose one for you. I have picked 



out one that has lately moulted (this moulting of scales is unique 



in whole order of common Cirripeds), and therefore has the 



scales on peduncle, with the teeth pretty sharp. The valves, of 



course, are not moulted, but the old layers scale or are rubbed 



off. I have not one with the basal calcareous cup, though several 



have been lent me. I wish you could see the basal cup. I feel 



STiRE it would confirm your opinion that it could not be the borer. 



I can see no reason yet to alter my opinion, that Lithotrya either 



crawls into the cavity, which it enlarges, or, if not, that the 



larva has the power of boring a hole, in which it fixes itseH and 



* = Balanus porcatus. Mon. Cirr. , Kay Soc, 1854, p. 256. 



