04 H. J. PI.KURE. 



than the first 90° of the torsion. This objection is to some 

 extent valid, but I think the process of completion of the 

 torsion is correlated with the evolution of the shell-rauscle^ 

 which I am at present endeavouring to investigate. 



If the supposition that the pre-torsional left side performed 

 most of the excretory function thus enables us to solve 

 satisfactorily the mystery of the counter-clockwise torsion, 

 this is surely a strong argument in its favour. I therefore 

 venture to hold, even more strongly than before, the view 

 supported in the earlier part of this paper, though it is not 

 in harmony with the opinion of a zoologist of M. Pelseneer's 

 eminence and insight. 



References. 



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Micr. Sci.,' 1883. 



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' Arcli. de Zool. exp.,' 2me serie, t. ii, 1884. 



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'Quart. Journ. Micr. Sci.,' June, 1892. 



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Journ. Micr. Sci.,' vol. xli, 1898. 



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