Edible Mollnsca of the Oregon Coast 197 



Mya arenaria in the Siiislaw River which in 1919 had become 

 depleted. Judging- from the experience of the past few years, the 

 most suitable time for artificial culture in this locality is in 

 November or early December, if high water does not prevent, 

 when large numbers of small clams from 10 to 25 mm. in length 

 are to be found near the surface of the nuul under patches of eel 

 grass. These should be replanted in depleted areas, the thinning- 

 out process permitting them to mature more rapidly than would 

 be possible in the aggregated groups in which they are naturally 

 found. The planting ma\- l)e accomplished very rapidly by fh.e 

 use of a sharp pointed stick for making shallow holes in the mud 

 into which the }oung clams are dropped siphon end up. 



5. Cardium corbis Martyn. 



The "cockle"' is the only hermaphroditic clam coming under 

 the observation of the writer on the Oregon coast. During the 

 late, fall and winter months it is rarely possible to distinguish the 

 ova or spermatozoa in this species. The sex elements begin to 

 appear in the spring, the spermatozoa being observed as early as 

 ^larch 29th at Newport, Yaquina Bay. Development of ova and 

 spermatozoa continues through the summer, spawning apparently 

 occurring from about the middle to the latter part of September. 

 On September 22nd ova appeared to be mature and the sperma- 

 tozoa were in a state of great activity. From October to March 

 the reproductive organs pass through phases of reorganization, the 

 oocytes and spermatocytes becoming dififerentiated in the early 

 spring. Histological sections through the reproductive organs 

 clearly show the spenuaries massed about the ovaries { Figure W 

 13. 14). 



6. Pholadidea penita (Conrad). 



An examination of the spermaries of males of this species 

 on iVIarch 27th at Nye Ueach revealed all stages of development, 

 in the same individual, from early spermatocytes to fully devel- 

 oped spermatozoa. No activit}- of the latter, however, could be 

 detected. On August 19th observations in the saiue locality indi- 

 cated large, well developed ova and apparently mature spermato- 



[-Ml 



