30 U.S. NATIONAL MUSEUM BULLETIN 25 8 



Statements defining the distribution of non-Californian genera are 

 included in table 34 ; this compilation thus represents a data sheet in 

 which subsequent tables and the following statements are to be verified 

 and seen in perspective. 



A total of 174 genera of rocky intertidal habitus, representing 1118 

 species, is known from the northern three fourths of the earth. Of 

 these, 63 genera have species occurring in California and these genera 

 have 747 species in all seas. Eleven of the genera are endemic to the 

 Calif ornian region but none has more than 2 species. 



The 102 genera not found in California are arranged into the follow- 

 ing geographic groups: 



North Atlantic Ocean and South Africa 36 



Australia, New Zealand and satellites 19 



Tropical 12 



Cold-temperate and arctic 10 



Subintertidal in California 8 



Northwestern Pacific Ocean 5 



Red Sea 3 



Antisubtropical 3 



Indian Ocean 3 



Baja California subtropical (Eriopisa, Ensai/ora) 2 



"Coldwater" 1 



102 



These assignments omit the genera Apherusa, Biancolina, Eriopi- 

 sella, Halirages, Laetmatophilus, Microprotopus, Palinnotus, Parame- 

 topa, Prothaumatelson, and Seba; their species are widely distributed 

 throughout the several oceans but presumably they do not occur in 

 the Californian intertidal. 



The first item of the above table reflects the enormous physical 

 barrier between California and the eastern Atlantic Ocean. The pan- 

 tropical genera not occurring in California are surprisingly few; 

 exploration of the Indonesian and Australian tropic shores has been 

 so scanty as to suggest that many more endemic genera will be found 

 in the Indo-Pacific tropics. The large number of Californian genera 

 shared with the northwestern Pacific Ocean is indicative of consider- 

 able faunal exchange between the regions. The few Caribbean genera 

 not shared with California are included in the tropical item. 



Comparisons of intertidal faunas between California and arctic- 

 subarctic regions are complicated by the poor representation of inter- 

 tidal faunas in high latitudes owing to ice-scouring; the intertidal 

 fauna of several tropical shores is also weakly developed because of 

 poor tidal amplitudes. 



In summary, the data of table 34 suggest that one third of the 

 world's intertidal genera occur in California, that one third of the 

 genera are excluded from California because of extensive physical 



