EXOTIC MOLLUSCA IN CALIFORNIA

Robert E. C. Stearns, APRIL 27, 1900, Science, pages 655-657

The number of foreign molluscan species in California has notably increased in the past few years, and includes both terrestrial and marine forms, detected by various collectors in and around San Francisco bay.

With the single exception mentioned below, the introduction of these exotic forms has been purely accidental, simple incidents in the usual course of business traffic or commercial interchange.

First, among the land shells we find the well known snail Helix aspersa, a common European species, largely used for food on the continent and familiar to persons who have patronized the restaurants of Paris. This species was intentionally introduced or 'planted,' in California over forty years ago by Mr. A. Delmas, of San Jose, Santa Clara county, who brought the stock firom France and turned it out among the vineyards on the west bank of the Guadalupe, a small river that flows northerly through Santa Clara Valley and empties into the southerly end of San Francisco bay near Alviso.

The soil where the snails were placed is a rich sandy loam and the place well shaded. When the summer heats reach the maximum, the Helices descend into the ground several feet, hiding in the cracks that form, as the ground dries, and the gopher-holes also furnish cool retreats and protection. The region above named is one of exceeding fertility. It was settled by a few French families. The introduction of H. aspersa by Mr. Delmas was made for edible purposes, or in common parlance 'with an eye to the pot.' Mrs. Bush, of the Normal School in San Jose, informs me that the snails have thriven, and have extended their territory from the starting point on the west bank of the stream to the easterly side, and have multiplied to such an extent, that in some instances they are troublesome in the gardens.

Mr. Delmas, the elder, also planted H. aspersa, in San Francisco and Los Angeles. I have never met with it in my collecting rambles in San Francisco or the outskirts of that city, nor heard of its having been detected by any collector. This particular plant was probably a failure, for a more unfavorable region than that of San Francisco forty years ago, with its cold sea winds, fog, sand-dunes and shifting sands and sparse ligneous scrubby vegetation it would be hard to find. At the present day the chances for success are altogether better, for the greater area of the city is covered by residences, with plats of grass, garden patches and flower-beds which are frequently watered and the general conditions are more promising. It would doubtless find a congenial environment in Golden Gate Park; its occurrence there is only a matter of time. I have learned recently that some party in the westerly section of the city propagates or did propagate H. aspersa. Mr. Fred L. Button, of Oakland, has informed me that it occurs1 in many of the gardens and private grounds in that place, and that one of his neighbors employed a man half a day 'cleaning them out of his garden.' Professor Keep, of the Mills College, last summer collected 'a fine living specimen' at Pacific Grove, Monterey, which is more than fifty miles south of the original Delmas plant on the Guadalupe.

It is now common in East Side Park and is also reported as occurring in Elysian Park in Los Angeles. These are, no doubt, the descendants of the stock planted by Delmas so many years ago.2

Mr. W. G. Binney, in his 'Terrestrial Air-breathing Mollusks of North America etc.' (Vol. V., July, 1878), reports H. aspersa, as found "In gardens in Charleston, S. C., and vicinity, where it has existed for fifty years; it has also been found at New Orleans and Baton Rouge; Portland, Maine; Nova Scotia; Santa Barbara, Cal.; Hayti; Santiago, Chili; etc.;" and Mr. Binney, if I am not mistaken, has raised them in his grounds at Burlington, N. J. As he says, "it evidently is a species peculiarly adapted to colonization."

I have always doubted its occurrence at Santa Barbara; it has never been confirmed by any collector to my knowledge. It was, in the first instance, credited to this place on the testimony of a communication to the Zoological Society of London, by Professor Edward Forbes, in which were described the shells collected in the course of surveying voyages of Captain Kellett and Lieutenant Wood of the Royal Navy, in the ships Herald and Pandora. The locality marks and labels were, unfortunately, badly mixed, and confusion was the inevitable result — Lower California species were credited to the far north, and so on.

A recent careful inquiry made for me by a friend utterly failed to obtain any data, showing its existence at Santa Barbara3 or thereabout at any time.

From the foregoing it will be seen that this species is fully established on both coasts of the United States and it is likely to extend its territorial domain in harmony with the prevailing spirit of the times.

Living Helix pomatia, a larger species, also European, has been imported by a leading grocery firm in San Francisco to supply its patrons. This is the snail par excellence of Continental epicures and was propagated on an extensive scale in the palmy days of ancient Rome as a dainty for the patrician palate on festal occasions; it is not unlikely that sooner or later this species also will be found in some congenial spot outside of the grocery store and in course of time become an inhabitant of California.

More than fifteen years ago a species of slug, Amalia Hewstoni, made its appearance in the grass plots of San Francisco; it was described by Dr. J. G. Cooper. It soon became a nuisance; even a regularly ordained clergyman spoke of it as 'a slimy brute'; however this may be, it has now 'expanded' its territory so as to include Seattle in the north and San Diego in the south. Dr. Pilsbry says it may be identical with the European A. gagates; it is not a native Californian. In addition to examples of Helix aspersa I have recently received specimens of Zonites (Vitrea) cellaria Müll. and Zonites (Vitrea) draparnaldi Beck, and the little bulimoid, B. ventrosus Fer, all from the lawns and flower-beds of Oakland, collected by Henry Hemphill.

Of the above, Z. cellaria has an almost world-wide distribution through the instrumentality of commerce. On the Atlantic side from Quebec to Charleston, S. C., along the coast, inland (in greenhouses) at Alleghany City, Pa., and Detroit, MIich. 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 detected 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 intimation of its occurrence in the British Isles though its absence from territory so comparatively near is remarkable. It has been reported from Bermuda. The occurrence of these European forms of Zonites and Bulimus in the gardens of Oakland are quite likely due to plant importations. A single example of the little Helicodiscus lineatus Say, was noticed by me several years ago, as having been collected in Oakland by Mr. Hemphill. Binney4 says of this peculiar form, that it "inhabits all of the Eastern, Central and Pacific Provinces, having been found from Gaspé 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 outside of Oakland, and only here in the single instance above meintioned. Mr. Hemphill has also collected Cochlicopa lubrica Müll. (= Ferrussacia subeylindrica L.) on Grizzly Peak back of the university grounds at Berkeley. This form has heretofore been reported from Oregon and Alaska, and presumably belongs to the circumboreal fauna.

1My esteemed friend, the late Dr. Newcomb, who lived in Oakland many years, may have planted some in his garden as an experiment. He had at one time on his grounds several living California forms of different species.

2I have been told that the employees in the park are of the opinion that it was incidentally introduced with foreign plants. They are not aware of the Delmas fact. Its presence in the park may, perhaps, be due to both.

3Vide my paper ' On Helix aspersa in California,' in Annals of New York Acad. Sciences, May, 1881, pp. 129-139.

4Manual of American Land Shells, Bull. U. S. N. Mus. No. 28, 1885, p. 75.