GAMMARIDEAN AMPHIPODA 19 



lished by encrusting organisms. Even in surf protected situations 

 rocks are poorly fouled with amphipod tubes. Nevertheless, the 

 number of tube dwellers in the Californian intertidal is large, 58 of 

 the 155+ species reported upon herein (Appendix II) being of that 

 habit (Isaeidae, Ischyroceridae, Corophiidae, Aoridae, Ampeliscidae, 

 and Ampithoidae). Only 8 species of sediment burrowers have been 

 found in the Californian intertidal and most of those are more abun- 

 dant on subintertidal soft bottoms than on intertidal epibioses. 



The important species of Amphipoda. — Several species of high 

 frequency, unusual habitat, or particular usefulness as indicators of 

 various ecological or zoogeographic conditions are discussed in 

 sequel. Problems of identification of some taxa also are emphasized. 

 Most of the minute details of occurrences, frequencies, and combina- 

 tions of species in various samples is left for the reader to examine 

 in the tables and appendices. 



The most abundant amphipod in the Californian intertidal (from 

 at least middle California southward) is Hyale rubra frequens (tables 

 3-24). This fact has long been known to naturalists gathering inter- 

 tidal plant materials and observing swarms of Hyale emerging when 

 disturbed by preservatives. Individuals of Hyale are especially 

 prevalent on surf grass and on stipes of Egregia, in the holdfasts of 

 kelps, and in tidepools partially filled with coralline algae. Although 

 the ubiquity of Hyale is monotonous, the individuals exhibit a degree 

 of phenotypy which should be studied ecogenetically. The typical 

 subspecies was described from New Zealand. The Californian sub- 

 species, H. r. frequens, as so considered herein, differs only in minor 

 characters not warranting full specific recognition in light of the 

 present state of knowledge and practice in amphipodan systematics. 

 The extreme density of this subspecies in the intertidal is good evi- 

 dence of the success of an epigenotype which may have ties across 

 vast distances of the sea, especially in view of its orientation to 

 plant materials which can be rafted. Study in progress on Galapagan 

 Amphipoda indicates a close connection between California and the 

 Galapagos Islands through rafting of plant materials. Vegetable 

 debris collected by the "Galathea" expedition at sea far from conti- 

 nental shores contains dense, apparently viable populations of amphi- 

 pods, not however H. rubra (material examined in 1961). Possibly 

 the poorly known Hyale nigra of Australia and the Red Sea is another 

 representative of the Hyale rw6ra-complex. 



The systematics of the genus should be studied with a view that a 

 Rassenkreis of hyalid taxa might exist throughout the Pacific Ocean. 

 The amphipodan fauna of California appears to have several con- 

 nections with that of Japan. For instance, Iwasa (1939) reported H. 

 schmidti, a species which is closest to the H. rubra of California. As 



