heavy, broadly ovate, moderately inflated shell with long, well-curved 

 posterior dorsal margin, which meets dorsal margin at a rounded angle. 

 Ligament deeply inset. Lunule well defined, heart-shaped. Escutcheon 

 indistinct. Numerous fine crowded concentric lines which are more 

 prominent and wider spaced on umbones. In adults, ridges are worn away 

 on median area of valves. Whitish, pale brown, grey or greyish brown, 

 sometimes with brown zigzag markings. Inside white, usually with purple 

 staining in region of muscle scars. 7 to 13 cm. Boreal, east coast of 

 North America and introduced in western European coastal waters, Trans- 

 atlantic, Caribbean, introduced in Humboldt Bay, Calif. Common. M. 

 stimpsoni Gould. Large, thick, heavy, moderately compressed, ovate- 

 trigonal shell resembling M. mercenaria in general appearance but more 

 produced anteriorly, with more pointed umbones. Concentric ridges more 

 lamellate, and radial riblets in grooves between ridges. Whitish. 7 to 

 10 cm. Japonic. Common. - J.L.M. 



427 



Darnell, Rezneat M. 1967. 



Organic detritus in relation to estuarine ecosystem. In Estuaries. G. H 

 Lauff (edj . Am. Assn. Adv. Sci., Pub. 83: 376-382. 



428 



Daugherty, F. M. , Jr. 1951. 



Effects of some chemicals used in oil well drilling on marine animals. 

 Sewage Industr. Wastes 23(10): 1282-1287. 



Mercenaria mercenaria was not used in these experiments. However, oysters 

 were used, and sometimes showed results different than that for fishes. 

 For that reason, the following are reported. Low toxicity compounds were 

 sodium acid pyrophosphate, Quadrafos, Impermex, sodium polyphosphate, and 

 Stabilite No. 9. These compounds were toxic to some test animals in 

 concentrations ranging from 500 to 7,500 ppm. Caustic soda, oil well 

 cement, Tannex, and white lime were fatal to many test animals in con- 

 centrations ranging from 70 to 450 ppm. These compounds have been 

 designated toxic materials. Baroco drilling clay, Aquagel Baroid drilling 

 mud, Carbonox, Jelflake, Fibertex, Mica, and Oilfos had no lethal effect 

 on any test animal, and were designated as non-toxic materials. Generally 

 low toxicity materials were more effective on oysters than fishes, whereas 

 the converse was true for toxic materials. - J.L.M. 



429 



Davenport, C. B. 1903. 



Animal ecology of the Cold Spring Harbor sand spit, with remarks on the 

 theory of adaptation. Decenn. Pub., Univ. Chicago 10: 157-176. 



Venus (Mercenaria) mercenaria is mentioned as one of the animals of the 

 submerged zone of the outer beach. - J.L.M. 



430 



Davis, Charles C. 1968. 



Mechanism of hatching in aquatic invertebrate eggs. Oceanogr. Mar. Biol. 

 Ann. Rev. 6: 325-376. 



The only reference to Venus mercenaria is to the work of Belding (1911), 

 abstracted elsewhere in this bibliography, in which he is reported to state 

 that the rather thick gelatinous covering of the egg is removed mechanically 

 by action of the larval (trochophoral) cilia after about 10 hrs. - J.L.M. 



431 



Davis, Harry C. 1949. 



On the culture of oyster larvae in the laboratory. Natl. Shellf. Assn. 

 Convention Add. 1949: 33-38. 



Larvae of the eastern oyster do not utilize as wide a variety of foods as 

 do larvae of the hard clam Venus mercenaria. - J.L.M, 



119 



