12 CALIFORNIA ACADEMY OF SCIENCES., 



Mr. Binnej also writes: "Thomson's shell was of the 

 European group of Z. acies," found about the Mediterranean 

 Sea. Mr. Thomson, having found no native species that 

 could be confounded with it, and being so exact as to local- 

 ity, as well as the cause of its extinction there, we must be- 

 lieve that the original stock was brought alive from 

 Southern Europe by ship, about 1850, and was placed 

 where it would probably become abundant, with a view of 

 supplying the market in future, just as F. pomaiia and 

 other species have been introduced into many parts of the 

 world for food supply ; also, P. aspersa, at Santa Barbara 

 and the Sandwich Islands. Though the location was well 

 chosen, there was not sufficient shelter to protect them 

 from the hogs. 



As almost any large species may be introduced, by 

 settlers, in this way, we may suppose that the single shell 

 of the Mexican P. huffoniana, found in 1857 by Mr. Holder, 

 on the bay shore at Alameda, was a relic of such an at- 

 tempted colonization. The strange occurrence of Orthalmis 

 zebra on Vancouver's Island, alive, as reported by Mr. Lord, 

 may be another instance. (See P. P. Carpenter's Report on 

 Mollusca of the West Coast of North America, 1863, p. 

 607.) 



As accidentall}^ introduced alive, I may refer to the spec- 

 imen of Adioracophorus found in a bale of the " Pulu" fern 

 brought'f rom the Sandwich Islands for mattress making. (See 

 Proc. Cal. Acad., v. 195, Nov., 1871.) I also received last 

 year, through Dr. Harkness, a very young Bulimoid shell, 

 living, found adhering to dried plants in a herbarium from 

 Panama. If it had been the warm season, it might have sur- 

 vived and grown in a moist garden or greenhouse, like 

 several other introduced species. 



Ophiogyra heligmoidea D'Orbiguy. (See Bull. 4, 218 ) 



Mr. H. Moores, of Columbus, Ohio, writes about this 

 shell: "The specimen was found just as stated, and was 



