SPAWNING HABITS OF CUMINGIA TELLINOIDES. 419 



week in June, July and the first half of August, as stated by 

 Morgan (Jour. Exp. ZooL, 1910). The production of eggs by 

 each female is continuous and covers the entire period. If 

 Cumingia which have spawned vigorously in the laboratory are 

 returned to their normal habitat for three weeks or a month, 

 they will again set free large quantities of eggs or sperm showing 

 that the supply is replenished. 



Experiment No. i. July 7, 1924. A stake was driven off 

 Ram Island and eighteen Cumingia were planted at its base. 

 All these had just spawned in abundance. On August 7, seven 

 of these Cumingia were again brought to the laboratory and 

 treated as usual to induce spawning. After forty minutes two 

 females had spawned heavily and three males had shed sperm 

 abundantly. One other female spawned after one and one half 

 hours. One of the seven did not spawn. The eggs of all these 

 were fertilized and grew into normal veligers. 



Experiment No. 2. July 6, 1926. Eighteen Cumingia that 

 had just spawned heavily were planted off Ram Island. On 

 August i, nine of these were again brought to the laboratory. 

 Three females spawned actively, three males shed sperm in 

 quantity, three did not spawn. 



These two experiments indicate that Cumingia spawns more 

 than once in a season and that the production of eggs and sperm 

 is continuous. 



There are indications that each female spawns two or three 

 times during the season when left in the natural habitat. This 

 inference is founded upon the facts that the eggs are constantly 

 produced and that spawning seems to be most common at full 

 moon and the days following full moon. Since there is no direct 

 evidence on this point, I do not care to insist upon it, except to 

 refer to the schedule of spawning experiments. (See tables, 

 Section III. on lunar periodicity.) There are clearly marked 

 variations in spawning activity which appear to be associated 

 with phases of the lunar cycle. 



Orton 15 has advocated the theory that the duration of the 

 spawning seasons of animals is determined by temperature. 

 According to his conception, spawning by any summer breeding 

 species begins in the spring when the water reaches a certain 



