232 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 22 



ZOOGEOGRAPHY OF THE BASIN ANIMALS 



So little is known of the wider distribution of the shelf and slope 

 fauna of the eastern Pacific that any remarks on the zoogeography 

 of the basin animals seem almost pointless. The fauna of the basins 

 is dominated by strictly bathyal species, although many basins have 

 more than 50% of their species of shelf origin. We consider most 

 of the shelf species to be strays and they rarely or never dominate a 

 sample. Only two of the basins, San Clemente and Velero, barely 

 extend into abyssal regions (2000 meters). As many of the important 

 polychaetes are new species (see Hartman, this paper) and have no 

 other distribution records, some may prove to be "hidden" abyssal 

 species having their shallowest occurrence in the deeper southern 

 California basins. Kirkegaard (1954) has listed eleven cosmopolitan 

 abyssal polychaetes. Six of these are eurybathic, of which two, Maldane 

 sarsi and Terebellides stroemi, occur in the basins. 



The crustaceans are still poorly known; they are a mixture of 

 species found at slope depths, a few new species and a number of badly 

 broken unidentified ones. The most common species are Heterophoxus 

 oculatus, a widespread shelf and slope species, found from Canada to 

 Ecuador, the giant unknown Apseudes sp., and several species of 

 Harpinia, all of which are new species. No known abyssal species have 

 been recognized. 



The echinoderms are largely well known species, half of which 

 live on the shelf, the other half of which are bathyal species with 

 wide distribution along the eastern Pacific margin. 



Among the mollusks, Cy do pec ten zephyrus Grau, 1959, is limited 

 to three of the basins. Solenogasters are largely new basin species. 



The occurrence of tube collar fragments of Pogonophora from 

 the deeper basins suggests faunal affinities with the abyssal sea floor 

 and thus remoter areas of the Pacific. 



There would appear to be four kinds of faunal components in the 

 basins: (1) the endemic and "normal" bathyal fauna; (2) a very 

 few species of abyssal origin which have their shallowest distributions 

 in the deeper basins, such as Hyalinoecia tubicola; (3) a large group 

 of small sized shelf species which descend into the basins and occupy 

 the benthos as vegetative individuals; (4) a smaller group of eury- 

 bathic species which are successful both on the shelf and in the basins. 



