abundant amounts of both, 40 ug/g wet weight of 5-HT and 40-90 ug/g wet 

 weight of Ach. - modified author's abstract. - J.L.M. 



388 



Cottrell, G. A., and M. Maser. 1967. 



Subcellular localization of 5-hydroxytryptamine and Substance X in molluscan 

 ganglia. Comp. Biochem. Physiol. 20(3): 901-906. 



5-Hydroxytryptamine (5HT) has been found in nervous tissue of many mollusks, 

 but it is particularly abundant in Mercenaria mercenaria. It is believed 

 that 5HT acts- as a neurohumor . Extracts of molluscan ganglia, including 

 those of hard clam, also contain a potent, unidentified, cardio-excitatory 

 factor presently called Substance X. Electron microscope studies have 

 demonstrated many types of small inclusion with vesicular profiles within 

 nerve axons and their fine branches. It is believed that 5HT may be associ- 

 ated with these vesicles. Study of density-gradient fractions of Mercenaria 

 ganglia homogenate under an electron microscope showed that Substance X is 

 associated with "uniformly granulated vesicles" of 1,000 to 3,000 Angstroms 

 diameter. It is still not possible to determine unequivocally the particular 

 type of subcellular inclusion with which the indolealkylamine 5HT is 

 associated. - J.L.M. 



389 



Cottrell, G. A., and N. N. Osborne. 1969. 



Localization and mode of actions of cardio-excitatory agents in molluscan 

 hearts. In Comparative Physiology of the Heart: Current Trends. F. V. 

 McCann (ed.) . Experientia Supplementum 15. Birkhauser Verlag, Basel, p. 

 220-231. 



References to Meraenaria (Venus) mercenaria are by citation of papers 

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



390 



Coues, E. 1871. 



Notes on the natural history of Fort Macon and vicinity. Proc. Phila. Acad. 

 Sci. 23: 120(131). 



According to Jacot (1921) , abstracted elsewhere in this bibliography, Coues 

 recorded Venus mercenaria, V. campechiensis , and V. mercenaria notata from 

 this area in N.C. It appears that Jacot gives Coues credit for the statement 

 that V. campechiensis was common inside the barrier beach. - J.L.M. 



391 



Coughlan, John, and Alan D. Ansell. 1964. 



A direct method for determining the pumping rate of siphonate bivalves. J. 

 Cons. 29 (2) : 205-213. 



Fourteen Venus mercenaria from 3 to 8.3 cm long were observed at 18° to 20°C. 

 Pumping rate varied directly with wt of clam, and with other indices of size. 

 Values obtained were higher than those of Rice and Smith (1958) , abstracted 

 elsewhere in this bibliography. Low rates were obtained when clam was 

 digging or when flow of water through aquarium was low. Normally, siphons 

 were extended a cm or 2 above the substrate, marginal tentacles extended and 

 out- turned. Typical and maximum pumping rates were always associated with 

 this appearance. When marginal tentacles were turned upwards or inwards, 

 often with slightly restricted siphonal aperture, pumping rate was reduced. 

 Changes in light intensity, slight tactile stimuli and water currents, and 

 static water conditions caused this reaction. For comparisons of pumping 

 rates, condition of. animals used should be described. The apparatus used 

 supplied dye to the clam and carried away the exhalent dye stream so as to 

 retain visibility. - J.L.M. 



108 



