42 AMERICAN JOURNAL 



NOTES ON MOLLUSCA OP MONTEREY BAY, CALIFORNIA. 



BY J. G. COOPER, M. D. 



Monterey is situated in lat. 36° 36', on nearly the same pa- 

 rallel as Norfolk, Va., Cadiz, Spain, and the northern part of 

 Niphon, Japan, and has of late become quite noted among those 

 interested in the conchology of western North America, as an 

 excellent locality for obtaining a large variety of species both of 

 the northern and southern temperate groups. Its situation and 

 local conditions are perhaps better suited for producing a large 

 number of marine species of mollusca than those of any other 

 point on the coast of temperate North America. It has the ad- 

 vantages of an insular and a continental station combined. 



Topography and Hydrography. 



The harbor of Monterey facing north and receiving a constant 

 but greatly moderated ocean swell, broken by the promontory 

 of Point Pinos, has no large influx of fresh water nearer than 

 the Salinas river, 17 miles northward. The rock forming the 

 shore west of the town is granite for three and a half miles, and 

 by disintegration has made a beach of clear white sand, extending 

 nearly around the bay, a distance of 70 miles. For about half 

 this distance sand hills border the shores, succeeded by cliffs of 

 soft post-pliocene sandstone, whicli border the north end of the 

 bay at Santa Cruz, 25 miles directly north of Monterey. This 

 sandstone also overlies the granite from near low-water to eight 

 fathoms depth, a mile northeast of town, forming a rocky bottom 

 for some distance off shore, and prevails throughout a large part 

 of the north end of the bay. 



Monterey has thus the conditions for preserving that salt- 

 ness and clearness of the water necessary for most marine 

 shells, together with a variety of stations suited for various 

 species, hard, immovable granite, soft sandstone for borers, 

 sand, and at 30 fms., mud. The estuaries, so numerous along 

 the coast, especially northward, are all more or less influential 

 in diminishing the number of species elsewhere, and even at 



