346 REPORT — 1856. 



70. Now let the student of geographical distribution of MoUusca begin by 

 observing the fauna of our own seas, and learn, from the invaluable work of 

 Forbes and Hanley, to discriminate species and eliminate those that are 

 spurious. Let him then, taking Philippi and M'Andrew as his guides, compare 

 them with the shells of the Atlantic and Mediterranean shores. Let him, with 

 Gould and DeKay, note both the similar and dissimilar forms on the shores of 

 the United States. Let him, after studying the very characteristic fauna of the 

 Caribbean Sea, again cross the Atlantic, and observe the reappearance of well- 

 known forms, in spite of the vast extent of ocean. Let him trace the fauna 

 of Senegal with Adanson, of the Guinea coast with Dunker, and of the Cape 

 and Port Natal \yith Krauss. Here let him enter on the vast Indo-Pacific 

 province; and, having taken-in the general conception of the fauna from any 

 collection of East Indian shells, let him examine its special districts, from 

 Akaba, to Easter Island in the latitude of the Gulf of California. Let him 

 learn from Cuming the vast variety of generic and specific forms which cul- 

 minate in the Philippines. Let him trace some of these westward even to the 

 northern extremity of the Red Sea, where they associate with types from the 

 Mediterranean and even the West Indies; and eastward from group to group 

 of the coral or volcanic islands in the vast expanse of the Pacific. Let him 

 note the reappearance of forms at the Cape and Australia, in spite of the 

 broad waters of the Indian Ocean. Let him learn from Nuttall the species 

 which are common to the Red Sea and the Sandwich Islands ; and from 

 Stutchbury those which abound both in New Holland and Tahiti. And, 

 having at every step in his inquiry found somewhat in common with the last; 

 having, when examining the shells of the Marquesas in the center of the 

 Pacific, found several conspicuous and well-known forms of the Asiatic Seas, 

 in spite of (in parts) the profound depth of ocean that lies between ; he will 

 naturally expect, as he reaches the American shores, to find also not a little 

 in common with the opposite shores. He crosses the vast unbroken expanse 

 of the West Pacific ; one flank of the hemisphere of waters, which of itself 

 almost rivals the Atlantic in extent. He pauses at the solitary Archipelago 

 of the Galapagos, in the very longitude of the Gulf of Mexico, guarding (as 

 it were) the great bay of Central America, and within 600 miles of its shores. 

 Even here his eye rests with pleasure on a few well-known Cones and other 

 forms, which have crossed the fathomless depths and come to claim kindred 

 with their molluscan brotherhood of the New World. But here they stop. 

 They could traverse half a world of waters. The human spirit that gives 

 them understanding and a voice, beholds them on the very threshold of the 

 promised continent, in whose bays and harbours, protected by the chain of 

 everlasting mountains, they shall find the goal of their long pilgrimage. But 

 the Word of the unknown Power has gone forth ; and the last narrow channel 

 they attempt to cross in vain. 



We speak now of the first general impression, without regard to excep- 

 tional cases : and the ascertained facts fully bear us out in saying that there 

 does not exist on the surface of the earth a more separate, independent 

 assemblage of moUusks than is to be found, under three great typical divi- 

 sions, from Oregon to Chili. Mr. Nuttall, in passing from California to the 

 Sandwich Islands, found only a ^?jo/>ow?/a; in common. Messrs. Cuming and 

 Hinds, both of whom had well explored the seas of the E. and W. Pacific, 

 and of whom the former made his great collections in the two equatorial 

 boundaries, with no inconsiderable research among the intermediate groups, 

 having compared about 2000 species from the two districts, came to the 



