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(as at Catalina Harbor on the outer side of Santa Catalina 

 Island). The absence from, or sparsity in, the inner 

 basins suggest that the species have different temperature 

 requirements, either as larvae or adults, or that there 

 are competitive factors which may be selective. 



The most abundant animals in the shallower bottoms 

 of Santa Monica Bay are various kinds of polychaetes, 

 smaller crustaceans (entoraostracans) and ophiuroidSo 

 Others which may be present in abundance at scattered 

 places are various types of raollusks, sipunculids, 

 echiuroids, a stalked brachiopod, nemerteans, and other 

 animals, most of which lie partly or wholly buried in the 

 sediments. 



Those in shallower depths are small in size, exceedingly 

 numerous, and perhaps have short life spans. Those in 

 moderate depths tend to be larger in size, fewer in numbers, 

 and are more diversified. The deepest bottoms (in the 

 basin) are impoverished or dead. 



The dominance of one or two species over extensive 

 areas, such as has been described from shallow bottoms 

 of western Europe (Danish authors), from Puget Sound 

 (Shelf ord and associates), from Long Island Sound (Sanders), 

 and other places, has not been observed in either the 

 Santa Monica or San Pedro areas. Instead, populations 

 exist in patterns much like a patch=work design, with 

 irregular or unpredictable recurrences and in various 

 kinds of associations A few species have been more or 



