THE NATURAL HISTORY OF CUMINGIA 

 TELLINOIDES. 



BENJAMIN H. GRAVE,! 

 WABASH COLLEGE (SEESSEL FELLOW 1926-27). 



INTRODUCTION. 



When it is considered that Cumingia is used extensively as a 

 source of material for embryological and experimental studies it 

 becomes a matter of importance to know its life history and its 

 availability at all times. An observation made several years ago 

 indicated that Cumingia exhibits a lunar periodicity in spawning 

 and led the writer to make an extended study of the species 

 covering a continuous period of five years. The laboratory 

 work was carried on at the Marine Biological Laboratory at 

 Woods Hole. 



With the perfecting of the diatom method of feeding embryos it 

 is possible to carry many marine larvae through metamorphosis 

 and thereby gain a knowledge of complete life histories where 

 only fragmentary knowledge has been possible before. In this 

 instance a pure culture of the diatom Nitschia, which was 

 isolated at the Plymouth Laboratory, was used. 2 The diatoms 

 at Woods Hole are not suitable for feeding because of the danger 

 of bacterial infection of the embryos. The Beaufort species 

 first used by Caswell Grave, on the other hand, grows in great 

 abundance in aquarium jars and may be fed without difficulty. 

 This diatom has the advantage over Nitschia in being relatively 

 short and thick instead of long and slender. Both of these 

 species should be propagated at marine laboratories for the use 

 of investigators. 



HABITAT. 



Cumingia tellinoides is found principally in sandy bottoms con- 

 taining a strong admixture of humus, with a sparse or moderate 



1 From the Osborn Zoological Laboratory, Yale University, New Haven, Conn., 

 and the Marine Biological Laboratory, Woods Hole, Massachusetts. 



2 The writer wishes to thank Dr. Isabella Gordon for a stock of this material. 



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