incurrent siphon, and on contraction of adductor muscles is discharged 

 through incurrent siphon, not between mantle folds below the siphon as in 

 some other bivalves. Direction of beat of cilia is never changed. Cilia 

 streams on surfaces of organs exposed to water are divided into 2 systems, 

 one leading to the mouth, the other bearing material outside the body. 

 Palps exercise general control over the 2 ciliary systems, determining 

 whether or not material shall enter digestive tract. Ciliary tracts on 

 palps have greater complexity and are more important than those of other 

 organs. There is no selection or separation of food organisms from other 

 water-borne particles; volume alone determines whether collected material 

 goes to the mouth or is discarded. A clam is able to feed only when waters 

 are comparatively clear, when diatoms are brought to gill surfaces a few at 

 a time. In muddy waters all suspended particles, of whatever kind, are led 

 to outgoing tracts. The sand-eating genus Maooma is an exception. All 

 ciliated areas produce mucus, which appears locally in response to stimulus 

 of foreign particles. Long-continued stimulation of any surface may produce 

 relatively enormous mucus secretion. The nervous system and muscles fre- 

 quently aid in operation of ciliary tracts, as in exposure of tracts by 

 spreading apart of palp folds, apposition of ventral margin and folds, of 

 palps and gills, gills and mantle, and gills and visceral mass. In addition 

 there are violent expelling contortions of gills, palps, and mantle edge, 

 sudden contractions of adductor muscles, and other movements. Directions 

 of flow in relation to major features of the anatomy are illustrated with 

 clear line drawings. - J.L.M. 



2155 



Kennish, M. J. 1977. 



Effects of thermal discharges on mortality of Mercenaria mercenaria in 

 Barnegat Bay, New Jersey. N. Am. Paleontol. Conv. II, J. Paleontol. 51, 

 Pt. II of III, Suppl. to No. 2: 17 (abstract 65). 



Thermal discharges from the Oyster Creek Nuclear Generating Station do not 

 affect mortality in natural populations of M. mercenaria in Barnegat Bay, 

 N. J. The analysis of daily growth increments and disturbance bands in 

 shell cross-sections of more than 300 specimens from death assemblages 

 collected from the mouth of Oyster Creek (strongly affected by thermal dis- 

 charges) and from three control sites (unaffected by thermal discharges) in 

 the Bay indicate that similar mortality patterns exist in all assemblages. 

 Statistically, there is no significant difference in the season of death 

 and the absolute age and size at the time of death for individuals sampled 

 from these four sites. This is revealed graphically by size-frequency and 

 age-frequency histograms which are nearly identical for each assemblage. 

 Each death assemblage is the result of natural rather than census mortality, 

 as is evidenced by its corresponding death-frequency histogram which shows 

 that individuals died at different times of the year. The peak frequency 

 of stress and death occurs in summer and winter when environmental condi- 

 tions are at extremes. - modified author's abstract - J.L.M. 



2156 



King, Kenneth, Jr. 1978. 



Distribution of Y - carboxyglutamic acid in calcified tissues. Biochim. 

 Biophys. Acta 542: 542-546. 



Y-carboxyglutamic acid, found in vertebrate mineralized tissues of bone and 

 dentin, was not found in any of six invertebrate species, including Mercen- 

 aria mercenaria, in the calcified skeletons. This indicates that it is not 

 obligatory for the calcification process in invertebrates. Invertebrates 

 as a group may lack the enzymatic capacity for biosynthesizing Y-carboxy- 

 glutamic acid. - modified author's summary - J.L.M. 



2157 



Koehn, Richard K., John G. Hall, and Anthony J. Zera. 1980. 



Parallel variation of genotype-dependent aminopeptidase-I activity between 

 Mytilus edulis and Mercenaria mercenaria. Mar. Biol. Lett. 1(5): 245-253. 



600 



