ON MOLLUSCA OF THE WEST COAST OF NORTH AMERICA. 161 



steep islands, of which the best known is Taboga (C. B. Adams, Pan. Shells, 

 pp. 19-21). — Mazatlan. On the north side of the bay is a "long neck of 

 narrow hills, [of primitive rock,] their sides exhibiting projecting crags and 

 deep indentations which the ocean has been lashing for ages. On the south 

 are rocky islands, but towards the south-west the harbour is open to the 

 broad Pacific, whence at times the sea rolls in with great fury " (Bartlett). 

 The harbour is in some places choked with shoals of large Pinnce, whose 

 sharp edges cut the boats (Belcher). Station has often much more to do 

 with the distribution of species than mere latitude: e.g. Venus gnidia is 

 found in muddy places from Peru to the Gulf of California, but is not 

 found on the prolific sandy floor of Acapulco harbour, where it is replaced 

 by the sand-loving V. neglecta. In some sandy situations, the dredge may 

 be used for hours without the smallest success ; while in others, where the 

 floor is varied, a short search will procure more than fifty species (Hinds). 

 — California. Along the coast of Upper California are primitive rocks, 

 chiefly granite and syenite. Near Santa Barbara are cliffs of shell limestone, 

 perhaps 200 feet high ; but their contents have not been recorded. Brooks 

 with hot springs issue from the primitive rocks, and there are abundant 

 traces of huge geological convulsions (Nuttall). The peninsula is of vol- 

 canic rock, and exhibits great diversity of climate. When, near Cape St. 

 Lucas, the thermometer stands between 60° and 70°, it may be found, near 

 the northern extremity, at the freezing point. The muddy marshes near 

 San Diego, &c, appear to be very prolific in bivalves ; as are the rocks in 

 Acmcece, which seem to culminate on this coast, whence they were first de- 

 scribed by Eschscholtz. " Observations on some points in the Physical Geo- 

 graphy of Oregon and Upper California, by Jas. D. Dana," will be found in 

 1 Siliiman's American Journal of Science and Art,' series 2, no. 21, May 1849, 

 p. 376. 



5. The Gulf of California (often, even in books of great pretension, 

 strangely called a bay) was discovered by a vessel detached from the expe- 

 dition of Cortez in 1533 (Dana), (1534, teste Hibbert). It was the Sea of 

 Cortez, and the Vermilion Sea of the early Spaniards. It is about 700 miles 

 long and from 40-120 wide. About the year 1697* it was colonized by a 

 party of Spanish Jesuits, who founded Loreto, La Paz, and San Jose on its 

 shores. The earliest shell known from its waters was the pearl oyster (Mar- 

 garitiphora fimbriata, Dkr.), to obtain which, about the seventeenth century, 

 the Spaniards employed from 600 to 800 divers ; the value of the pearls ob- 

 tained annually being estimated at 60,000 dollars. So exhausting was this 

 traffic, that the fishery is now almost entirely abandoned. Occasionally, 

 however, a ship-load of pearl shell is sent to Liverpool, and sold for manu- 

 facturing purposes. Among the sweepings from one of these loads was found 

 the finest specimen known of Placunanomia pernoides, remarkable for its 

 reappearance on the Gambia coast. There appears to have been a treaty 

 with Spain as far back as 1786, allowing of some trade between this country 

 and the Mexican shores ; but there is no trace of much intercourse before 

 the Declaration of Independence in 1821. In 1826 a direct treaty was 

 formed between England and Mexico, and from that time the Californian 

 and W. Mexican coast has ceased to be a terra incognita to English natu- 

 ralists. Still, however, our knowledge of the shores and deep waters of the 

 Gulf (especially of its northern extremity), and of the peninsula of Cali- 

 fornia, is most fragmentary. The present Report contains the first account 

 at all verging towards accuracy and completeness, of the fauna at its mouth. 

 The 117 species collected on the shores of Upper California by our country- 

 * Hibbert : 1642, Blackie, Imp. Gaz. 



1856. m 



