Page:Familiar letters of Henry David Thoreau.djvu/387

 asT.40.] TO MARSTON WATSON. 361

chance to have (and I am pretty well provided), a^e Kirby and Spence (the fullest), Knapp (&quot; Journal of a Naturalist &quot;), &quot; The Library of Entertaining Knowledge &quot; (^Rennie), a French work, etc., etc. ; but there is no minute, scientific description in any of these. This is apparently a female of the genus Lampyris ; but Kirby and Spence say that there are nearly two hun dred species of this genus alone. The one com monly referred to by English writers is the Lampyris noctiluea ; but judging from Kirby and Spence s description, and from the descrip tion and plate in the French work, this is not that one, for, besides other differences, both say that the light proceeds from the abdomen. Per haps the worms exhibited by Durkee (whose statement to the Boston Society of Natural His tory, second July meeting, in the &quot; Traveller &quot; of August 12, 1857, I send you) were the same with these. I do not see how they could be the L. noctiluca, as he states.

I expect to go to Cambridge before long, and if I get any more light on this subject I will in form you. The two worms are still alive.

I shall be glad to receive the Drosera at any time, if you chance to come across it. I am looking over London s &quot; Arboretum,&quot; which we have added to our Library, and it occurs to me that it was written expressly for you, and