2054 



Yevich, P. P., and M. M. Barry. 1970. 



Histopathologic finding in molluscs exposed to pollutants. Abstract of 

 papers, Session III, Sect. 4, 33rd Ann. Meeting Am. Soc . Limnol . Oceanogr. 

 Univ. R.I., August 25-29. 



Abstract not seen. - J.L.M. 



2055 



Yonge, C. M. 1928. 



Feeding mechanisms in the invertebrates. Biol. Rev. 3(1): 21-76. 



In this extensive review paper the author cites the conclusion of Colton 

 (1908), abstracted elsewhere in this bibliography, that Syaotypus and Fulgur 

 (and probably Nassa and Lunatia) never bore through the shells of 

 lamellibranchs . Fulgur seizes the strong shell of Venus in the hollow of its 

 foot, brings it against the margin of its own shell, and by contractions of 

 the columellar muscle forces the valves together so that fragments are broken 

 off. The process is repeated until the crack is about 3 mm wide. The 

 proboscis may then be flattened and forced in, or the clam be killed with a 

 secretion, or the shell may be forced open. The extensive bibliography 

 contains 189 references plus mention of 2 other exhaustive bibliographies. 



- J.L.M. and M.W.S. 



2056 



Yonge, C. M. 1930. 



The crystalline style of the mollusca and a carnivorous habit cannot normally 

 co-exist. Nature 125(3151): 444-445. 



Meraenaria (Venus) meraenaria is not mentioned. Development of a carnivorous 

 habit demands, with rare exceptions, presence of an enzyme capable of 

 breaking down flesh of prey into soluble polypeptides and amino acids. The 

 crystalline style of lamellibranchs and many gastropods is formed of protein 

 of a globulin type, which could be digested readily by any extracellular 

 proteoclastic enzyme. It follows that a mollusk cannot normally possess a 

 style and be a carnivore. The point is emphasized by a review of mollusks 

 that have a style. The only extracellular enzyme is that set free by 

 dissolution in the stomach of the head of the style, and that acts 

 exclusively on starch and glycogen. Zooplankton may survive passage through 

 the gut. Minute particles of animal matter may be ingested and digested by 

 wandering phagocytes which pass through the gut wall into the lumen, then 

 back into the tissues. The one exception is in the septibranchs, which have 

 lost the ciliary feeding mechanism and have developed a muscular feeding 

 mechanism which allows them to swallow small dead or dying animal prey. The 

 stomach acts as a crushing gizzard. The small style is apparently func- 

 tionless. Food is digested intracellularly in tubules of digestive 

 diverticula. - J.L.M. 



2057 



Yonge, C. M. 1946. 



Digestion of animals by lamellibranchs. Nature 157(3996): 729. 



Meraenaria (Venus) meraenaria is not mentioned. It had been suggested that 

 living and disintegrating animals in the gut of lamellibranchs are digested 

 by protease secreted by digestive diverticula. The author disagrees. 

 Phagocytic blood cells pass in great numbers into the lumen. They contain 

 proteolytic and lipolytic enzymes, which may be released into stomach fluids 

 when phagocytes cytolize. Presence of animals in the stomach may stimulate 

 migration of phagocytes into the lumen. Extracellular enzymes obviously are 

 not usually present in sufficient quantity to digest the crystalline style. 



- J.L.M. 



570 



