VI U.S. NATIONAL MUSEUM BULLETIN 258 



Hyale rubra jrequens and Amphilochus litoralis. Holdfasts of kelps 

 in intertidal zones are small but heavily populated with Amphipoda, 

 most of which are identical with those of the Phyllospadix-pelv etiid 

 zone. Kelp holdfasts from subintertidal depths have a different 

 amphipodan fauna from those of intertidal zones. More than 35 

 species of Amphipoda have been found in one holdfast of Macrocystis 

 pyrifera in 3 m. of water. The largest Amphipoda of Californian 

 coastal shallows, Cymadusa uncinata, inhabit the largest kelps. Ar- 

 ticulated coralline algae are densely populated with a poorly diversified 

 amphipodan fauna and few Amphipoda are restricted to that substrate. 

 In contrast, more than a dozen species of Amphipoda inhabit sponges 

 and tunicates obligatorily. Interstitial rock nestlers and intertidal 

 sedimentary burrowers occurring under rocks also are very scarce. 



Those taxonomic problems of particular interest concern the 

 identifications and nomenclature of various species of Hyale, Lysian- 

 assa, Elasmopus, and Ischyrocerus. 



