THE ROCK OYSTER. 



165 



face of one valve. The species is found from San 

 Diego to Puget sound. 



We come now to a notable species, Hirinites gigan- 

 teus, Gray, Hin'-ni-tes gi-gan'-te-us, Fig. 138. It is 

 sometimes called the Rock Oyster, and sometimes 

 the Winter Shell. In its early life it has a free, 

 symmetrical shell, looking like a Pecten. Its shell 

 is then distinguished by its very unequal ears and the 



twelve prominent, serrated 

 ribs on its upper valve. It 

 soon settles down for life in 

 some convenient and shel- 

 tered spot, such as the inside 

 of an old Haliotis-shell, 

 fastens its lower valve to 

 this support, and yields 

 itself up to circumstances. 

 It soon looses its regularity 

 of form and becomes oyster- 

 shaped, developing some- 

 times one valve and some- 

 times the other, as oppor- 

 tunity offers; twisting itself 

 to the right or to the left, 

 Fig. 138. and becoming so distorted 



that it seems to have wholly forgotten its youthful 

 o-race. Its outside color varies from yellow to brown, 

 while within it is pure white, except a rich purple 

 area at the hinge-line. This purple color is very 

 permanent, and may be seen even in the fragments of 

 shells which are picked up along the beach. The 

 ligament is internal, lodged in a deep, narrow pit; 

 the muscle-scar is smooth and very large. 



