160 SHELLS OF LOWER CALIFORNIA— STEARNS. 



Besides tlie specimens of the above, received in the Stearns collection 

 the National Museum contains three of the original lot collected by Dr. 

 Veatch on Cerros Island (Nos. 8715, 8716, U. S. K. M.), two collected 

 by Lieut. Pond [l^o. 103610, U. S. N. M.), five received from Mr. Belding, 

 collected by him near San Quentin Bay (No. 34525, U. S. N. M.), one ex- 

 ample from an island in said bay (No. 73j33, U. S. N. M.), numerous ex- 

 amples from Cerros Island (U. S. Fish Commission, No. 102121, U. S. N. 

 M.),. and two examples collected by Henry W. Henshaw on Cerros 

 Island (No. 63986, U. S. N. M.). 



HELIX (ARIONTA) L^EVIS, Pfeiffer. 



= Eujparypha Icevis, BiNNEY. 

 + Folymita Iwvis, Tryon. 



Abundant^ dead. Ascunsiou Island, Lower California (No. 58527, 

 U. S. N. M.). 



This island is of small area; it is situated south of Cedros, or Cerros, 

 in latitude 27°. The above, as well as H. pandora Fbs., are probably 

 dwarfed varieties of areolata. A large number, all dead, were obtained 

 by Mr. Fisher. They exhibit a rather wide range of variation, par- 

 ticularly in elevation, and the tubercle on the columella is shown 

 to be an inconstant character; the color markings are variable, as 

 in areolata. From Fisher's notes I learn that he found the fore- 

 going " on plateaus from 50 to 300 feet above the sea level, in great 

 numbers, embedded in sand mixed with guano. Found only four 

 plants, small shrubs (individuals), on the island, otherwise utterly des- 

 titute of vegetation." In conversation Mr. Fisher informed me that 

 the specimens he obtained had been scratched out of the sand and 

 guano by the sea-fowls in excavating or making a hollow for nesting 

 purposes. It is quite evident that the faunal and tioral character of 

 the island has undergone a great change within quite recent times. 

 Not many years ago when these snails were living, and before the sea- 

 birds took possession of it, the surface of the island, which quite likely 

 was never very densely clothed with vegetation, exhibited, we may pre- 

 sume, about the same floral aspect as others in the same general region. 

 The birds, disturbed elsewhere, or from some other cause, invaded the 

 territory of H. Iwvis, and in destroying the vegetation also extinguished 

 the snails and such other forms of animal life as were dependent upon 

 it for food. Fisher told me that he failed absolutely to detect a single 

 living individual of H. kevis. Here we have an instance where the 

 extension of the specific area of one form or class of animal life, oblit- 

 erated or diminished the territory or specific area of another. It would 

 be interesting to know of similar instances, for doubtless such have 

 been observed and noted. Mr. Orcutt collected numerous examples of 

 this species, living and in fine condition, near El Rosario Mission, in latii- 

 tude 29° 50'. He found them " abundant under Agave iShawi, on higk 



