NO. 1 hartman: quantitative survey 145 



Thus, sample 44b yielded more than 50 species of annelids, with more 

 than 850 individuals, in addition to many other invertebrates (see 

 Analyses, above). A nearby sample, 45a, contained several large jack- 

 knife clams, phoronids, ophiuroids, more than 43 species of annelids with 

 hundreds of individuals, few of which were common to the adjacent 

 sample, 44b. The Chaetopterus association, sample 43a, is quite different 

 from that in 44a, even though both come from shallow bottoms near 

 shore. Adjacent samples, 123a and 123b, about a minute of longitude 

 apart, differ considerably in the species comprising their populations (see 

 Analyses, above). 



The effects of the breakwater along the outer side of the Los Angeles 

 Harbor, are well shown by comparison of samples 44b and 44a (see 

 Analyses, above). Sample 44a, beyond the breakwater, has many speci- 

 mens of a larger terebellid, Streblosoma sp., enteropneusts, ophiuroids 

 and holothuroids. Sample 44b, in the Outer Harbor behind the break- 

 water, contains many specimens of Nereis procera, Tharyx parvus, Cos- 

 sura sp., Arnphicteis scaphobranchiata, and other annelids. 



Similar habitats, such as sandy bottoms along shore, differ in their 

 dominant animals, even though ecological conditions appear the same. 

 For example, sands off Anaheim Bay (sample 50) support an archian- 

 nelid, Saccocirrus, and a pelecypod, Crenella, in considerable numbers. 

 Sands off Los Angeles breakwater (sample 63b) have large numbers of 

 an anemone, Harenactis; those north of Palos Verdes Point (sample 14) 

 support large numbers of a sipunculid in dead tests of Dendraster, to- 

 gether with annelids of the genera Pisione and Aricidea. 



Masses of biological detritus, such as the thick layers of dead lamp 

 shells, Laqueus calif ornicus and Terebratalia transversa (from samples 

 186b, 238a and 224e), and the associations of glass sponge (see text, 

 below) have been found to contain a great variety of animals. 



The number of specimens in some samples runs very high, with some 

 groups, but seldom single species, of animals dominant. In all soft bot- 

 toms (rocky bottoms have not been successfully sampled with the grabs), 

 the marine annelids are most abundant, followed by ophiuroids, pelec- 

 ypods, holothurians, gastropods, amphipods, scaphopods, burrowing anem- 

 ones, echiuroids, nemerteans and other invertebrates. Thus, sample 

 108, off Newport Beach pier, in 17 fms, measuring 1.26 cu. ft., yielded 

 63 species and more than 500 individuals of annelids, in addition to many 

 ophiuroids, holothurians, pelecypods, gastropods, amphipods, and other 

 groups. A sample from Redondo Canyon (6b) in 161 fms, containing 

 2.8 cu. ft. of mud, had 6 large specimens of an undescribed species of 



