NO. 2 OLGA hartman: submarine canyons 23 



Pectinaria calif orniensis, Pholo'e glabra and Prionospio spp. Most of 

 the members of this assemblage occur also in shelf depths throughout 

 the Santa Monica Bay area. The green shelf echiuroid, Listriolobus 

 pelodes, is replaced by the canyon one, the red Arhynchite sp., in 146 

 meters, and a green mud fauna occurs at 560 to 61 1 meters. 



The axis was sampled in depths of 137 to 611 meters; its sedi- 

 ments are mostly mud or sand. In its shallowest depths the sediments 

 are black, have an odor of hydrogen sulfide and contain dead shelly 

 debris. The larger animals are the cone-tube worm, Pectinaria, the 

 stinging worm, Chloeia pinnata, and numerous smaller shelf species 

 of polychaetes. The capitellid, Heteromastus filobranchus, is abundant 

 throughout much of the canyon from 148 to 560 meters, and accounts 

 for the abundance of fecal pellets (see Emery and Hiilsemann, 

 1962) found in the sediments. Brissopsid urchins are mainly Brisaster 

 townsendi, in 378 to 611 meters. A large red ribbon nemertean, 

 Cerebratulus, is taken singly in most samples from axes depths. The 

 largest polychaetes are Onuphis vexillaria, humbrineris index. Aphro- 

 dita sp. and Glycera aniericana. Brada pilosa, a bristle-cage worm, 

 attains high concentrations in depths of 503 and 560 meters. The large 

 red echiuroid, Arhynchite sp., is generally encountered in large samples 

 from muddy sediments. The samples from greatest depth contain 

 representatives of deepwater species, resembling those of more northern 

 canyons. 



The brackish capitellid, Capitella capitata subspp., is most abundant 

 at 148 meters. Black mud and oil globules with some animals are taken 

 in 246 and 282 meters. Plant and woody debris, dead and broken 

 tubes of Pectinaria are most abundant at 298 and 344 meters. Notably 

 sparse or absent are representatives of amphiodid ophiuroids, the 

 green Listriolobus, crustaceans especially amphipods, surface forms 

 such as sea whips, ceriantharians, and many more. 



The basin slope was sampled in 167 to 556 meters. The samples 

 contain gray mud, sand, stones, shelly rubble and waxy lumps from 

 shallowest parts, and sandy or silty mud with many animals and 

 foraminiferan remains in 310 to 556 meters. 



The fan was sampled in depths from 602 to 853 meters, here 

 considered in three groups: 602 to 751 meters, 769 to 800 m, and 808 

 to 853 m. The first group, with eight samples, has a considerable 

 amount of specific diversity, the second group has far less, and the 

 third group is nearly without life. At 602 meters a small sea pen, 



