63 



Most of the characteristic living species are listed in Table II, but the 



following species can be considered the most abundant infaunal inver- 

 tebrates : 



Prosobranchiata Crassatella gibbosa 



Solariella triplostephanus Nemocardium pazianum 



Natica grayi Chione mariae 



Murex recurvirostris Macoma siliqua 



Fusin us dupettithouarsi Trigon iocardia gran if era 

 Pleuroliria albicarinata 



Echinoidea 

 Clypeasier europacificus 



Asteroidea 

 Luidia Columbia Liitken 



Lamellibranchiata Ophioroidea 



Anadara nux Amphigyptis perplexa 



A number of the species from these 13 stations as given on Table II 

 were also taken in shallower water and a few were found in deeper waters. 

 All stations were taken on sand bottom in an area where bottom temper- 

 atures range between 30° and H'^C. and the waters are well-oxygenated. 

 As an assemblage, there is a considerable difference between this one and 

 the one inshore of it, in that there was an enormous number of mollusk 

 species found only as dead shell, and not usually found living in these 

 depths elsewhere along the coast. Most of these species normally live in 

 depths of from 1 to 30 meters. A list of them can be compiled from Table I 

 by noting all species in the complete list which were taken from the 13 

 stations shown on fig. 19. These dead, but shallower shells, are important 

 to the paleontologist, however, in that they are part of an assemblage 

 which will eventually become buried and form a distinct fossil deposit 

 indicative of a transgressive sea. It is presumed (and somewhat sub- 

 stantiated by carbon- 14 dates) that the sand deposits in which these shells 

 are found have resulted from lowered sea level during the early part of the 

 Holocene. The shells of animals which once lived close to shore became 

 mixed with deeper species as the sea level rose, and the shoreline moved 

 inwards. It is known that strand line deposits resulting from lowered sea 

 level at around 7,000 to 1 1 ,000 years ago occur at depths of from about 

 40 to 80 meters throughout the world (Curray, 1960, 1962). Figs. 20a 

 and b show the distribution of two of the typical decapods found in this 

 environment, Cancer amphioetus and Randallia americana. The distribution 

 of two mollusks, the gastropod, Solariella triplostephanus, and the pele- 

 cypod, Trigoniocardia biangulata are shown in figs. 21a and b. The distri- 



