140 SHELLS OF LOWER CALIFOBNTA— STEARNS. vol.xvii. 



the Pacific that miji^lit possibly transport drift material from the regions 

 where these si)ecies are known to live, and tlms (;onvey and enable them 

 to make a lodgment or gain a foothold on the western coast of the 

 continent. In the gulf region the currents sweep in the opposite direc- 

 tion, that is, to the westward. It is possible that these exotic forms 

 have been introduced as an incident of commerce. 



For many years vessels seeking a return cargo from various places 

 in Indo-Pacific waters have visited the gulf region, especially the 

 Tres Marias islands, for the dyewoods that are found there, and which 

 at various periods have furnished quite a large business to vessels 

 seeking return freights. Vessels bound to the gulf j)ortsin such cases 

 would be in ballast, and if from Indo-Pacific regions the ballast would, 

 it is probable, consist in the main of coral blocks or fragments of reef- 

 rock, the chinks of which ordinarily furnish a hiding place for mollus- 

 can species, and other small forms of marine life. Upon arriving at 

 the port or embarcadero before loading, the ballast would be dumped 

 overboard, and with it such animals, living or dead, as were secreted 

 among, attached to, or contained in it. The Tres Marias and Altata 

 are well known loading places for the dyewoods trade; the latter being 

 an embarcadero for interior regions, where the dyewoods are cut. In 

 one instance I collected several specimens of Orthalicus nndatxs and a 

 si)ecies of Bulhmdus that had concealed themselves among the dyewood 

 and were transported with it to- San Francisco. Upon discharging the 

 cargo, in throwing the freight ashore, the snails were jarred out. Some 

 of them were picked up on the wharf and others in the hold of the 

 vessel after the cargo was discharged. 



Besides the dyewoods, salt from the Carmen Island works and orchilla 

 furnish export cargoes in whole or in part. The extent of the traffic 

 in these Mexican exports varies very much one year or period compared 

 with another. At the time of the Franco-Mexican war, or rather the 

 invasion of Mexico by the French, the commerce of the gulf was 

 greatly increased. It was during this period that large and important 

 additions were made to the Stearns Collection, through arrangements 

 made with parties employed in the coastwise trade between California 

 and west Mexican ports. No such opportunity for obtaining the shells 

 of the gulf region has occurred since, nor is likely to for many years. 

 In addition to the collection made by Mr. Fisher, I have, in a few 

 instances, added to the list localities visited by other friends and the 

 species collected by them. In this connection, the names of Capt. A. 

 Forrer, of Dr. William M. Gabb, whose collections, made at San Juauico 

 and Loreto, Lower California, in February, 1807, were published by 

 me in 1873,* and the late Henry Edwards, well known as an excellent 

 actor and in scientific circles as an accomplished entomologist and 

 writer on entomological subjects, who contributed a few species that 

 were found by him at Mazatlan and vicinity in 1873, appear occasion- 



' Proc. Cal. Acad. Sciences, July, 1872. 



