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THE AMEBIC AX NATURALIST [Vol. LII 



Molluscs abound on all the reefs. There is a tremen- 

 dous range of size, structure, habitat and generic repre- 

 sentation. The marine molluscan fauna has never re- 

 ceived adequate attention, as scientific interest has cen- 

 tered upon the unique terrestrial and arboreal forms. 

 There are about 20 species of bivalves (Pelecypoda) that 

 are fairly common. These include such genera as Mytilus, 

 Perna, Area, Ostrea, Anomia, Pecten, Tellma, Cadokia, 

 Cytherea, Venus, Cardium and Chama. Tellma sugosa, 

 the Olepe, is, according to Bryan, "the most important 

 shell-bearing mollusc" in the islands. The famous pearl 

 shell, Avicula margaritifera, of the South Pacific, does not 

 occur in Hawaiian waters. The Hawaiian pearl oyster, 

 pa, Margaritifera fimbriata, has a shell often 3 or 4 inches 

 broad, with a brilliant iridescent interior. It is the 

 species which gave Pearl Harbor its name. In the early 

 days the collecting of pa was a royal monopoly, like the 

 collecting of sandalwood. The pearl-shell was used by 

 the Hawaiians chiefly for making fish-hooks, and for the 

 curious shell-eyes of their wooden gods. A true pearl- 

 bearing species also occurs at Pearl Harbor and other 

 localities in the group in the deeper offshore waters. The 

 edible oysters are represented by Ostrea rosea, which is 

 not of sufficient abundance to permit commercial exploita- 

 tion. 



The chitons and their allies, Amphineura, are uncom- 

 mon in the shallows, but a thorough systematic survey 

 would undoubtedly bring to light many additional forms. 

 The true chitons, Placophora, are confined largely to the 

 shallows, and apparently are herbivorous, feeding on 

 minute algae and diatoms. The Aplacophora as worm- 

 like, shell-less creatures, with the body beset with cal- 

 careous spicules. They are wholly absent from the lit- 

 toral zone, occurring only at considerable depths-3,000 

 ft. and in some instances down to 7,500 ft. They are car- 

 nivorous and subsist on such small animals as hvdroids 

 and coral polyps. 



The univaives or Gasteropods are by far the most 



