of the Pacific Shores of North America. 523 



open, and presents a succession of inaccessible, perpendic- 

 ular, rocky cliffs alternating with barren beaches of sand, 

 all being completely exposed to the action of the breakers, 

 which roll in upon them with the concentrated force of the 

 storms of a wide and unbroken ocean. There is a want of 

 variety in station, and a paucity of inlets, bays and islands, 

 in the protected nooks of which such animals as we are 

 now to consider usually find shelter. Extensive dredging 

 operations would no doubt bring to light many species in 

 places where the nature of the bottom is favorable, but 

 the submarine zone in which the depth of water is not too 

 great for the existence of animal life, is narrow ; since, as 

 we might judge from the mountainous character of the 

 shores, the sea-bottom dips far beyond the reach of the 

 ordinary sounding-line, in close proximity with the land. 



There are but two important inlets on the coast, and of 

 these Puget Sound is without doubt the best locality for 

 researches among the marine invertebrata. The Bay of 

 San Francisco, from the admixture with its waters of the 

 turbid flood of two large rivers, and the smallness of the 

 gate which admits to it the clear water of the ocean, is 

 nearly barren of animal life except at its entrance. At a 

 former epoch, and one geologically speaking quite recent, 

 the sea had a much freer sweep through the bay. On its 

 shores I have often observed extensive superficial deposits 

 of shells, of the same species that now live on the coast, 

 (Mytili, Ostrece, etc.) lying in a horizontal stratum at a slight 

 elevation above the present high-water mark. These are 

 particularly abundant beneath the soil in the valleys of 

 Petaluma and Sonoma, extending thence toward the sea 

 at Bodega ; and "here perhaps an ancient gate existed. 

 Another opening may have been situated at the southern 

 extremity, through what is now the Valley of Santa Clara. 



A preponderance of Asteriadce will be noticed among 

 the Echinodermata now to be described. The restricted 

 genus Asterias (Aster acanthion, Mull, et Trosch.) is par- 



