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Extracted from the Proceedings of the Academy of Natural Sciences of Philadelphia, 
January 28, 1879. | 
ON THE LAND SHELLS OF THE MEXICAN ISLAND OF GUADELUPE, 
COLLECTED BY DR. E. PALMER. 
BY W. G BINNEY. 
The island of Guadelupe is about 220 miles from San Diego, off 
the west coast of Lower California. Its molluscous fauna has for 
the first time been made known by the researches of Dr. Edward 
_ Palmer, who visited it in 1875. He found numerous fragments of 
snail shells which had been devoured by a species of mouse, the 
only inhabitant of the island. These fragments appear to belong 
to Arionta Rowelli, Newcomb (see L. & F. W. Sh. of N. A. I. p. 
185), a species found in Lower California. Some perfect shells 
were found, among them a smaller variety. Arzonta facta, New- 
comb, was also found, the variety with open umbilicus, like that 
form found fossil on San Nicolas Island, California. 
The most interesting discovery, however, is that of living spe- 
cimens of Binneya notabilis, a species found also on the California 
sland of Santa Barbara. There is strong reason for believing 
the Mexican genus Xanthonyx to be synonymous with Binneya. 
We may suppose, therefore, that from Mexico the genus has been 
introduced by the usual means of distribution to this island of 
Guadelupe, and thence to Santa Barbara. Thus,:its presence on 
the latter island is accounted for, which was not the case when 
we had only the mainland of California to look to, as its absence 
there has been proved. So, also, in the case of Arionta facta, we 
may account for its distribution by supposing it to have been in- 
troduced from some unknown locality on the mainland to Guade- 
lupe first, and thence to the California islands. 
The specimens collected are in the Museum of the Boston 
Society of Natural History. 
Four species of Orthoptera were collected also. One of these 
is shown by Dr. Scudder to be identical with a Mexican species, 
and two of the others have also been found at San Diego. 
