NO. 2 OLGA HARTMAN: SUBMARINE CANYONS 53 



Catalina canyon has a shelf fauna in its upper h'mits. In 559 meters 

 and beyond, the fauna is a deepwater one, characterized by the presence 

 of brissopsids, solenogasters, Dacrydium, a small white clam, Ophio- 

 musium jolliensis, an ophiuroid, and various polychaetes. Holothuroids 

 occur chiefly above 379 meters, whereas brissopsid urchins are below 

 362 meters. 



San Clemente rift valley : — Sampling procedures were unsatisfactory 

 to obtain biomass data ; the samples are discussed more completely 

 elsewhere. 



Tanner canyon: — This was sampled in depths of 298 to 1298 

 meters. Biomass values ranged as follows: 



64.2 gm/ sq.m., in 496 m. 6.2 gm/ sq.m., in 1298 m. 



51.4 gm/ sq.m., in 603 m. 4.0 gm/ sq.m., in 644 m. 



43.4 gm/ sq.m., in 298 m. 3.8 gm/ sq.m., in 8 1 3 m. 



Percentages of weights by major animal groups are as follows: 



In 298 meters, with 22.3 grams: 



2 echinoids 61.9% 



polychaetes 25.1 

 ophiuroids 8.1 



mollusks 2.7 



crustaceans 2.2 



In 496 meters, with 32.1 grams: 



1 Turcicula (snail) 36.96% 



polychaetes 36.18 



ophiuroids 17.91 



an echinoid 2.72 



others 6.23 



In 644 meters, with 2.0 grams : 



polychaetes 55.0% 



holothurians 25.0 



mollusks 20.0 



In 813 meters, with 2.9 grams: 



polychaetes 51.7% 



ophiuroids 48.3 



In 1298 meters, with 3.1 grams: 



polychaetes 58.1% 



sipunculids 41.9 



