April 27, 1900.] 



SCIENCE, 



657 



European A. gagates; it is not a native Cali- 

 fornia n. In addition to examples of He- 

 lix a»persa I have recently received speci- 

 mens of Zonites ( Vitrea) cellaria Miill. and 

 Zonites ( Vitrea) draparnaldi Beck, and the 

 little bulimoid, B. ventrosus Fer, all from 

 the lawns and flower-beds of Oakland, col- 

 lected by Henry Hemphill.. 



Of the above, Z. cellaria has an almost 

 world-wide distribution through the instru- 

 mentality of commerce. On the Atlantic 

 side from Quebec to Charleston, S. C, 

 along the coast, inland (in greenhouses) 

 at Alleghany City, Pa., and Detroit, Mich. 

 Z. draparnaldi is found in the greenhouses 

 of Seattle according to Dr. Pilsbry and 

 has before been reported as occurring in 

 Oakland. The little bulimoid form de- 

 tected by Mr. Hemphill has not, to my 

 knowledge, been previously found anywhere 

 in North America. It is a continental 

 species. I do not find in the books, any in- 

 timation of its occurrence in the British 

 Isles though its absence from territorj^ so 

 comparatively near is remarkable. It has 

 been reported from Bermuda. The occur- 

 rence of these European forms of Zonites 

 and Bulimics in the gardens of Oakland are 

 quite likely due to plant importations. A 

 single example of the little Helieodiscus 

 lineatus Say, was noticed by me several 

 years ago, as having been collected in Oak- 

 land by Mr. Hemphill. Binney * says of 

 this peculiar form, that it " inhabits all of 

 the Eastern, Central and Pacific Provinces, 

 having been found from Gaspe to Texas ; 

 on the Rio Chama, New Mexico ; in Idaho ; 

 in Oakland, Cal." This is misleading, as 

 it has not been detected anywhere within 

 the Pacific province as defined by him out- 

 side of Oakland, and only here in the sin- 

 gle instance above mentioned. Mr. Hemp- 

 hill has also collected Coehlicopa lubrica 

 Miill. {^ Ferriissacia aubcylindrica L.) on 



* Manual oE American Land Shells, Bull. U. S. N. 

 Mus. No. 28, 1885,'p. 75. 



Grizzly Peak back of the university grounds 

 at Berkeley. This form has heretofore been 

 reported from Oregon and Alaska, and pre- 

 sumably belongs to the circumboreal ikuna, 



MARINE SPECIES. 



Having completed our review of the ter- 

 restrial species, we may now consider the 

 marine forms, which are confined almost 

 exclusively to San Francisco bay. 



The presence of the "Virginia oyster in 

 this region is wholly due to business enter- 

 prise ; its introduction dates from about the 

 time of the completion of the overland 

 railways. Upon the completion and opera- 

 tion of the transcontinental lines certain of 

 the San Francisco oyster dealers com- 

 menced the importation by the carload of 

 small or seed oysters, one and two years 

 old, from the Atlantic side, for planting in 

 San Francisco bay, where after a couple of 

 years they attain a marketable size. These 

 importations of Ostrea Virginiea have been 

 continued ever since, as this species, owing 

 to some unfavorable peculiarities in the new 

 environment, does not increase sufficiently 

 to meet the demands of trade. 



The importations of the seed oysters for 

 the nine years, ending with 1895,* amounted 

 to 15,271,000 pounds, costing $350,000. 



As an incident of these importations we 

 find several familiar species have been un- 

 intentionally introduced, some of which 

 have already established themselves, and 

 appear to be permanently naturalized, as 

 well as others that are gaining a foothold. 



The most important of these accidental 

 introductions is the common sand-clam, 

 Mya arenaria of the Atlantic Seaboard, vari- 

 ously known as the ' soft-shelled,' ' squirt,' 

 ' long-necked,' clam, and ' mananose. ' 



There probably has never been in the his- 

 tory of commerce an instance of an acci- 

 dentally introduced animal species that has 

 proved so economically valuable as this. 

 * Report of U. S. Fish Com. for 1896. 



