444 NATURAL HISTORY OF HAWAII. 



Kiwalao, is cream color with black teeth. A third species is dark-brown in 

 color, with the hinge-line somewhat elongated and marked with fan-like lines 

 radiating from the beak. 



A species of the pearl oyster family ^ occurs at Pearl Harbor. The com- 

 mon species "pa" is often three or four inches or more across. The hinge-line 

 in the common pearl oyster ^ found here is long and straight, without teeth, 

 and is produced to form wing-like projections of the shell at either side of 

 the beak, which is much nearer the middle of the hinge. Without doubt it was 

 the presence of this shell with the iridescent interior, occurring at Pearl Har- 

 bor, on Oahu, that gave that sheet of water its name, i^ilthough they belong to 

 the same sub-family,'^ they are not the famous pearl shell '^ of the South Pacific 

 islands. However, a pearl-bearing species is found in Pearl Harbor and at cer- 

 tain other places about the group in the deeper water offshore, and pearls were 

 found to some extent by the natives, but the pa was chiefly used by them for 

 making fishhooks and to some extent in making the curious shell-eyes for their 

 wooden gods. 



Fine specimens of the chest or ark shell,° locally know^n as kupukele, are 

 to be found living in the water and bedded in the solid rock in certain locali- 

 ties in the uplifted coral reef about Pearl City. They, in common with other 

 species of the famih^^*^ have the beak near the middle of the hinge. The 

 hinge-line is strong and straight and is furnished with fine interlocking teeth. 

 The outside is fluted with jDronounced squarish riblets. A second species ^^ 

 found w^ashed up on the sand beaches is oblong in shape, and in the dead shell 

 the wdiitish surface is marked with many fine riblets which in old age become 

 broken up into squarish points by the lines of growth. The inside of the shell 

 within the pallial line is also roughened liy lines radiating from the beak. 



The true oysters, the scallops and the saddle 03'sters differ from other 

 bivalves in that they have but one, instead of two, adductor muscles for pulling 

 the shells together. They lie on their sides instead of standing on edge as other 

 bivalves do, and the under valve becomes flattened or otherwise modified in 

 consequence. 



There is a large species of extinct oyster ^- to be found in the uplifted beds 

 about Pearl Harbor, but there also occurs a smaller living species ^^ seldom more 

 than two inches in length. On account of its sharp edge it is called pioeoe by 

 the natives. It makes a rough, rude, irregular foliated shell, the edge inter- 

 locking by numerous notch-like folds. They are too small and scarce to be 

 used extensively for food. Nevertheless, they, and their extinct cousins, indi- 

 cate that a commercial species could be grown in the islands if the proper kinds 

 were introduced and proper care taken in their planting, despite the fact that 

 efforts in this field have so far proved unsuccessful. 



° ArictiUdif. ''■ Mmiinritifera fitiihritita. ' AvicuUncp. ^ Avirula inari/aritifera. 



° Area. ^^ Arcidcc. '^^ Area Candida. ^- Ostrea reta.ia. ^^ Ostrea rosacea. 



