NATURAL HISTORY OF CUMINGIA TELLINOIDES. 2OQ 



growth of eel grass, and where the tidal currents run swiftly 

 as in narrow channels. The vertical distribution is not great, 

 being a little above and below low tide mark. 



The animal is readily dug with a spade at low tide and separated 

 from the dirt with a coarse sieve. Under favorable conditions 

 one can collect three or four dozen in the course of an hour. 

 It has long siphons which enable it to lie inches below the surface 

 of the bottom and yet feed from the water in the manner of 

 lamellibranch mollusks generally, the food being chiefly diatoms 

 and floating particles of organic matter. It is rather particular 

 about the kind of bottom and the nature of the water currents 

 and is therefore restricted in its distribution. 



THE SPAWNING SEASON*. 



Cumingia begins to spawn about the middle of June and 

 continues until the middle of September. One can usually 

 depend upon getting eggs in abundance until about August 20. 

 At that time there is likely to be a lull or often a complete 

 cessation in spawning until the first of September or until the 

 next full moon. Eggs can usually be obtained in considerable 

 quantity during the first half of September. Not all individuals 

 are spawning in September and few are spawning heavily as a 

 rule. Each adult spawns more than once during the season and 

 the production of gametes is apparently continuous. 



METHOD OF SECURING EGGS. 



Cumingia spawn very readily in the laboratory but it is 

 necessary to treat them according to schedule. Experience has 

 shown that the best way to obtain clean eggs or sperm is to 

 wash the animals free from all sediment and isolate them in 

 small stender dishes half filled with sea water. When so placed 

 in sea water and left undisturbed for an hour or less they extend 

 their siphons and spawn if sexually mature. The eggs or sperm 

 are thrown forcibly from the dorsal siphon as they accumulate 

 in the supra-branchial chambers. The sexes are separate and 

 may be distinguished by their color. The males are white and 

 the females pink. The shell is not heavy so that the color of 

 the gonads shows through more or less. 



