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The mode of feeding of Orepidula, with an account of 

 the current-producing mechanism in the mantle 

 cavity, and some remarks on the mode of feeding 

 in Gastropods and Lamellibranchs. 



By 

 J. H. Orton, A.R.C.Sc, B.Sc, 



Assistant Naturalist at the Plyvioutli Laboratory. 

 With Fififures 1-20 in the text. 



TABLE OF CONTENTS. 



I. Introduction .... 



II. The mode of feeding in Crepidula 



III. Mechanism causing the food-cuvrents in Crepidula 



IV. Summary of account of current-producing mechanism, and mode of feeding 



in Crepidula .... 

 V. Function of the radula in Crepidula 

 VI. Resemblance of the function of gill of Crepidula to that of Lamellibranch gill 

 VII. The mode of feeding in the oyster and other Lamellibranchs 

 VIII. An explanation of the direction of Evolution in Lamellibranchs 

 IX. The current-producing mechanism in Lamellibranchs 



X. The ciliation of the gill of Nucula ^^^^ ^ 

 XI. The bearing of the Gill Chai'^^it^fs of Nucula on the Relationship of the 

 Protobranchia to the Filibranchia . 

 XII. A comparison of the mode of feeding in Lamellibranchs and Crepidula 



XIII. The mode of feeding in the allies of Crejiidula 



XIV. The current-producing mechanism in other Gastropods 

 XV. Significance of chain formation in the mode of feeding of Crepidula 



XVI. The mandibles of Crepidula 

 XVII. Summary .... 



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I. INTEODUCTIOK 



The manner in which the slipper-limpet, Crepidula fornicata, feeds has 

 apparently puzzled all the naturalists who have interested themselves 

 in this animal, as may be gathered from what follows. Crepidula — 

 like its allies the whelks and other pectinibranchiate Gastropods — 

 has a well-developed radula, a fact which leads one to infer that the 

 animal lives a marauding life. But both Conklin and myself have 

 shown that Crepidula settles down permanently at an early age to 



