GAMMARIDEAN AMPHIPODA 17 



of Amphipoda in Calif ornian coastal shallows; the largest individuals 

 have been found only in association with the largest marine plant. 

 Possibly this is the amphipod, reported by scuba divers, which rolls 

 up the blade margins' of Macrocystis and "stitches" (?cements) them 

 into dwelling cylinders; however, all the specimens at hand of G. 

 uncinata have been collected in rhizomes. The striking Ceradocus 

 spinicauda, of northern affinity and occurring intertidally at Coos 

 Bay, Oregon, apparently is obligatorily associated with marine 

 plants but in southern California it occurs only subintertidally. 



A surprisingly large number of species appears to be restricted 

 to kelp holdfasts or to occur most frequently in those habitats. 

 Amphipoda believed to be restricted to holdfasts are: Amphilochus 

 picadurm, Ceradocus spinicauda, Cymadusa uncinata, Eurystheus 

 mamolus, Lembos ?concavus, Lignophliantis pyrijera (the borer), 

 Liljeborgia geminata, Maera lupana, Melita appendiculata, and Najna 

 'tconsiliorum. Those species occurring more frequently in holdfasts 

 than in other habitats are: Ampithoe humeralis (a northern species 

 rare in southern California), Ampithoe lindbergi (abundant in Egregia- 

 stipes), Chevalia aviculae, Corophium uenoi (also in red-algal fields, 

 on diopatrid -bottoms and in lagoons), Heterophlias seclusus escabrosa, 

 and Maera simile. A third list to follow includes those species appar- 

 ently occurring as strays in holdfasts; these Amphipoda are otherwise 

 far more frequent on soft bottoms: Ampelisca pugetica, Batea trans- 

 versa (abundant in subintertidal clumps of small fleshy algae in the 

 Channel Islands), Lepidepecreum gurjanovae, Metaphoxus fultoni, 

 Orchomene pacifica, and Synchelidium sp. M (sand bottoms and 

 semi-neritic). 



Corallinaeceous algal-dwellers. — Jointed coralline algae were 

 sampled at Carmel (station 48-H-2), Hazard Canyon (42-B-4-X, 

 42-T-ll), Pt. Dume (table 11), and La Jolla (45-0-1, 0-2, T-l, 

 W-3 and W-4). At La Jolla and Corona del Mar, corallines were so 

 inextricably mixed with the Phyllospadix-j) elvetiid flora that the zone 

 has been denoted herein by the term " Phyllospadix-cor &\\m&ceous." 



In the larger group samples of relatively pure stands of corallines 

 the overwhelmingly dominant amphipod is Hyale rubra frequens, 

 which is 7 to 10 times more numerous than the second most abundant 

 species. The algal stand at La Jolla is probably more typical of 

 southern California than that stand at sand scoured Pt. Dume. 

 Thus, 5 samples from La Jolla reveal 27 species of Amphipoda and 

 5 from Pt. Dume only 16 species. Pontogeneia rostrata is a conspic- 

 uous subdominant at Pt. Dume, but it is rare at La Jolla and is not 

 replaced by another abundant pontogeneiid. Probably the southern 

 limits of Pontogeneia rostrata occur in this region of southern Cali- 

 fornia. At La Jolla conspicuous subdominants are Elasmopus rapax 



