266 CHARLES HOWARD EDMONDSON 



tion. The spawning season of the species in this locaUty is in 

 the late summer, extending into September. The energy of the 

 animal is at a low ebb after spawning, the following months being 

 a period of physical restoration and of increasing resistant power. 



A relatively small number of animals survived when environ- 

 mental modifications were brought about by restoring the mol- 

 luscs, after the operation, to the sandy soil near the river shore 

 instead of returning them to the soft, black mud of the bed from 

 which they were taken. Although these latter experiments were 

 conducted during the winter months, I believe the change of soil, 

 the longer time out of water between tides, and other accompa- 

 nying conditions may have contributed to the high death rate in 

 the tests carried out along the river bank. 



The experiments were commenced on February 23, 1918, and 

 conducted continuously for twelve months, one series following 

 another, each series consisting of from one to three dozen clams 

 with crystalline styles removed, each group being reserved for 

 examination at a definite interval after the operation, the inter- 

 vals depending somewhat upon the condition of the tides, but 

 ranging from six to seventy-four days. It was found that this 

 latter time was approximately the period required for the com- 

 plete reformation of the crystalline style in this species. 



3. THE MATURE CRYSTALLINE STYLE IN MYA ARENARIA 



Among the common marine lamellibranchs of the northwest 

 coast great variation in the resistant character of the crystalline 

 style may be observed. In some forms a complete dissolution 

 of the style readily occurs if the animal is removed from its 

 natural environment or subjected to an extended period of star- 

 vation. Among the species which may be mentioned in this 

 connection are Cardium corbis, Saxidomus giganteus, Saxido- 

 mus nuttallii, Paphya staminea, etc. Owing to the shape of the 

 crystalline styles of the species just mentioned, it will be found 

 when the animals are taken out of the water and subjected to 

 unusual conditions that the styles soon creep into the stomachs 

 and coil themselves up there, resulting in the style sacs being 

 empty long before the crystalline styles are actually dissolved. 



