THE WEST AMEEICAN SCIENTIST. 61 



[ Correspondence. ] 



ON LOWER CALIFORNIA LAND SHELLS. 



June 26th, 1886. 

 My Dear Mr. Orcutt : 



Thanks again for shells sent with yours of 16th. The Binneya is, indeed, the 

 notabilis. The genus has been described from Mexico as Xanthonyx, and, before 

 seeing your shells, I thought you might have stumbled on a Mexican species. Your 

 discoveiy of this genus in Lower California is a very happy one, throwing light 

 upon the presence of Binneya on Santa Barbara Island. Hitherto the neirest point 

 of finding the genus was the Mexican island of Guadalupe. I supposed it was 

 brought thence to Sta. Barbara by birds. Now we may suppose the same agency 

 has been at work, but from the more neighboring Lower California. At all events, 

 it appears that the Cali ornia islands have been peopled from the Mexican fauna. 



The larger Pupa is chordata, Pfr. — a species before known only from Mazatlan, 

 as far as my knowledge goes. I have drawn your specimens by camera lucida, in 

 case you want a figure. They are less attenuated at the apex, and have more 

 whorls than the individual figured in Land and Fresh Water Shells of N. A., 

 I. On second thought, I send you my camera sketches. Keep them. 



The ofther Lower California Pupa I have not yet identified. It requires to do 

 so a great deal of eyesight, which I prefer keeping for our own molluscs. Then, 

 again, I have not kept au courant of late years with Mexican species. I advise your 

 sending the shell to H. Crosse, 25 rue Tronchefc, at Paris. 



The San Diego Pupa does not seem to me arizonensis, and I cannot spare eyes 

 to determinate it. In my books are enlarged views of the described species of Pupa, 

 by means of which and a pocket lens you can readily make this out, I detest Pupa 

 and Succinea above all things conchological. I give you a camera lucida drawing of 

 the outline of your shell — the aperture was still unfinished when the tube of my 

 microscope slid down on the shell and smashed it, much to my delight. 



Helix levis, Pfr., sent by you, is surely that species, though it may be a variety 

 of areolata. I have drawing of jaw, tongue and gentalia at your disposal, if you 

 want them. The jaw is like that of Arionta. There are five distant, robust ribs, 

 denticulating either margin: jaw arched, little attenuated, blunt. Lingual mem- 

 brane with 38-1-38 teeth, as in Stearnsiana, etc. 



Genital system quite like what I have figured (Terr. Moll., V) for Tryoni in 

 general arrangement. The accessory organ, probably dart sac, in levis is longer, 

 and only the thread-like organ attached to its base was detected by me, not the 

 sponge-like process (1 in my figure of Tryoni), but I may have overlooked that. 



Now for H. Stearnsiana. The species was originally found by Gabb under 

 stumps of maguey from Santo Tomas to Rosario. It corresponded with your 1321, 

 which has the same genitalia as I have described for Stearnsiana, but this is nega- 

 tive evidence. I think all the shells you send are forms of the same species, which 

 1 have always found variable in Lower California — but I am not infallible, and 

 what to me seems varietal difference, to you may appear specific distinction, and 

 you may be as near right as I. Still, I think most couchologists would agree with 



