357 



Clem, J. David. 1971. 



Sanitary shellfish: Keeping a step ahead. Fed. Drug. Adm. Pap. 5(5): 15-17. 



Activities of Federal and State governments and shellfish industry to produce 

 non-contaminated shellfish since the typhoid fever epidemic of 1924-25 are 

 reviewed. In judging the adequacy of classification of shellfish grounds 

 from which mollusks can be safely harvested for market, the State control 

 agency must consider the most unfavorable pollution and worst hydrographic 

 conditions. Safe or "approved areas are separated from obviously polluted 

 areas by buffer zones. Mechanical breakdowns, natural disasters, and human 

 error must be allowed for. Two closed areas have been designated in sewage 

 sludge dump sites in the inner part of New York Bight and off Delaware Bay, 

 with a radius of 6 mi from the point of dumping. These areas are patrolled 

 by the Coast Guard. A compilation of commercial shellfish growing areas in 

 the U.S. in 1966 showed that of about 10 million acres of shellfish grounds 

 2 million were closed by pollution. The Shellfish Sanitation Program Manual 

 of Operations requires resurveys every 10 yrs , or more frequently if cir- 

 cumstances warrant. A resurvey may be made necessary by passage of a 

 hurricane over an area. These activities relate to all commercial shellfish 

 species, including hard clam. - J.L.M. 



358 



Clench, William J. 1939. 



Mollusks that "muscle in". New England Nat. 3: 12-13. 



A popular account of the methods by which Busy con opens a bivalve, such as 

 Venus (Mevcenavia) campechiensis . The whelk usually envelops a clam with 

 its foot and opens the valves by suction. The method observed was that in 

 which the whelk inserted the edge of its own shell between the valves of 

 the clam and broke away small parts until a hole was made large enough to 

 insert the proboscis, to feed on soft parts of the clam with its radula. 

 The whelk shell also was damaged. Relatively few whelk shells were found, 

 however, which had suffered such damage. Some parasitic snails have 

 developed a strong tooth or spine at the edge of the opercular opening to 

 aid the opening process. - J.L.M. 



359 



Clench, William J. 1948. 



A remarkable malformed specimen of Venus campechiensis Gmelin. Revista Soc. 

 Malacol. 6 (1) : 10. 



A right valve only was found on the beach at Sanibel Island, Fla. Three 

 photographs show that the valve was coiled like a gastropod, the axis of the 

 coil almost in a single plane. The left valve must have been much smaller, 

 probably only large enough to close the "aperture". - J.L.M. 



360 



Cobb, William Robert. 1972. 



Penetration of calcium carbonate substrata by Cliona aetata, a marine 

 burrowing sponge. Diss. Abstr. Int. B. Sci . Eng. 32(9): 5531-B-5532-B 

 (Ph.D. thesis, Univ. R.I., 1971, 175 p.). 



A special type of Cliona cell, with capacity to etch, removes small cal- 

 careous chips from the substratum. Dissolution of shell was confined to a 

 narrow zone of contact between cell edge and substratum. Penetration was 

 effected by a rounding-up of the cell edge, formation of a curvilinear 

 etching around the circumference of each etching cell, undercutting of the 

 substratum, enclosure of a chip by the cell, and release of the chip at 

 the site of penetration. Circular etchings, crevice-like undercuts, cup- 

 shaped pits, and angular multifaceted chips were the microscopic patterns 

 and products. General appearance of each was the same in Iceland spar, 

 or in shells of bivalves including Mercenaria mercenaria. The etching 

 agent released by penetrating cells dissolved organic and crystalline 

 components of bivalve shells. Burrowing and massive forms of Cliona celata 

 began penetration by a variety of asexual methods. - J.L.M. 



100 



