2l8 BENJAMIN H. GRAVE. 



or until nearly first quarter is the period of free spawning. 

 During the summer of 1922 Cumingia was not spawning from 

 August 15 until September I. On September i spawning 

 revived and eggs were obtained in abundance for several days 

 following. (September 5 was full moon in 1922.) The cessation 

 in mid-August may be described as sudden and the recovery in 

 September was equally striking. This complete break was 

 observed by others who were experimenting with Cumingia eggs. 

 Records of other years show that such a clear-cut periodicity 

 has been observed before but is not demonstrable every year. 

 There is, however, almost without exception, a reduced spawning 

 at the time of the first quarter of the moon not only in August 

 but in June and July as well. There can be little doubt, there- 

 fore, that we are dealing here with a true lunar periodicity. 

 There is always a period of from one to five days during the season 

 when eggs are not obtainable after which spawning is revised. 



SUMMARY. 



The breeding season extends from the second week in June to 

 the middle of September. The gametes are produced continu- 

 ously and spawning occurs more than once. A rhythm is present 

 which is interpreted to be a lunar periodicity. 



The rate of embryonic development is variable, but under usual 

 conditions the larva metamorphoses in about three weeks. 

 Growth during the first two years is comparatively rapid and 

 average adult size is attained at the end of the second year. 

 Fortunate individuals may continue to live and grow for four 

 years. Sexual maturity is reached in one year and spawning is 

 abundant although greater quantities of gametes are produced 

 during the second year. 



The egg of Cumingia is subject to polyspermy and abnormal 

 development often occurs if too heavily inseminated. The un- 

 fertilized egg will retain its vitality for approximately nine to 

 twelve hours during which it is capable of developing normally. 

 The spermatozoa when set free in sea water usually die within 

 four to nine hours, a few die within three hours and a few live for 

 twelve or fifteen hours. 



The Cumingia egg is favorable material for experimental study 



