Growth was correlated with diatom abundance. Growth was slower in 

 sediments of high silt-clay content than in sediment with low silt-clay. 

 Silt-clay inhibits growth possibly by interfering with feeding by re- 

 ducing sediment permeability, producing growth inhibitory substances or 

 requiring energy expenditure to clear filtering apparatus. - D.L. 



1490 



Pratt, Henry Sherring. 19 35. 



A manual of the common invertebrate animals exclusive of insects (2nd ed) . 

 P. Blakiston's Son & Co., Inc., Philadelphia, xviii+854 p. 



Phylum Mollusca, Class Pelecypoda (Lamellibranchiata) , Order Teleodesmacea, 

 Family Veneridae: Venus mercenaria L. Mollusca: bilaterally symmetrical, 

 unsegmented animals in which the body is usually encased in a calcareous 

 shell, and is made up of 4 parts, visceral mass, head, mantle and foot. 

 Pelecypoda: Symmetrical mollusks with a double or bivalve shell and mantle, 

 and without a head. Teleodesmacea: gills reticulate, right and left lobes 

 of mantle more or less connected on ventral and hinder margins, siphons 

 usually well developed, 2 adductors about equal in size, shell porcellaneous 

 or obscurely prismatic, never nacreous, ligament behind umbo, hinge teeth 

 separated into distinct cardinals and laterals, usually with a hinge plate 

 and a pallial sinus, sexes usually separate, many families. Veneridae: shell 

 regular, heavy; ligament external; hinge usually with 3 diverging teeth in 

 each valve; laterals not constant; pallial sinus usually small; mantle open 

 below; several hundred species, in all seas, in tropics often very brightly 

 colored. Venus: shell thick and round or ovate, inner lower margin minutely 

 crenulated; cardinal teeth 3 in each valve; laterals absent; lunule distinct; 

 ligament prominent; siphons short, unequal, and more or less separated; 

 mantle margins fringed; numerous species, in all seas. V. mercenaria L. - 

 hard-shell clam, little-neck clam, quahog. Shell ovate or heart-shaped; 

 anterior end short; posterior end rounded; umbo directed forwards; surface 

 a dirty white, with prominent, sharp, concentric ridges; inner surface smooth, 

 dull white, lower margin violet or purple; length 11 cm; width 6 cm; height 

 9 cm. Gulf of St. Lawrence to Texas, on sandy and muddy bottoms in shallow 

 water; very common south of Cape Cod; used extensively for food; shells were 

 used by Indians for manufacture of wampum, the violet portion forming the 

 most valuable pieces. - J.L.M. 



1491 



Pratt, S. D. 1973. 



Benthic fauna. In Coastal and Offshore Environmental Inventory - Cape 

 Hatteras to Nantucket Shoals. Univ. R.I:, Grad. School Oceanogr., Mar. 

 Expt. Sta., Kingston, Mar. Pub. Ser. 2: 5-1 to 5-70. 



Since the decline of oyster stocks in Great South Bay and Moriches Bay, 

 Long Island, N.Y. , Mercenaria mercenaria and Mytilus edulis make up a large 

 part of wet-weight biomass in sandy and transitional sediments. M. 

 mercenaria can tolerate freezing, but succumbs at -6°C. At any temp hard 

 clam dies when 64% of its tissue water has been removed as ice. It is 

 sometimes infested by the polychaete Polydora. Busy con carica and 

 B. aanaliculatum are voracious predators on hard clam and other bivalves. 

 Infrequent references to hard clam in this chapter are cited from published 

 papers abstracted elsewhere in this bibliography. - J.L.M. 



1492 



Prescott, Benjamin, and George Caldes. 1967. 



Chemical studies of an antitumor substance from clams. Fed. Proc. 26(2): 314 

 (abstract 336) . 



The antitumor principle of clam liver extract (species not named, but pre- 

 sumably Mercenaria mercenaria) is a greenish to white amorphous powder, 

 non-dialyzable, forming a colloidal solution in water. Activity is 

 destroyed when solutions are heated to 70° or higher (presumably C) for 

 30 min. Antitumor activity of aqueous solutions is not destroyed at pH 8.0. 



416 



