It is well known that the shells of land-mollusca are affected by the abundance of lime in different districts. Isidore Geoffroy Saint-Hilaire (23/42. 'Hist. Nat Gen.' tome 3 page 402.) gives the case of Helix lactea, which has recently been carried from Spain to the South of France and to the Rio Plata, and in both countries now presents a distinct appearance, but whether this has resulted from food or climate is not known. With respect to the common oyster, Mr. F. Buckland informs me that he can generally distinguish the shells from different districts; young oysters brought from Wales and laid down in beds where "natives" are indigenous, in the short space of two months begin to assume the "native" character. M. Costa (23/43. 'Bull. de La Soc. Imp. d'Acclimat.' tome 8 page 351.) has recorded a much more remarkable case of the same nature, namely, that young shells taken from the shores of England and placed in the Mediterranean, at once altered their manner of growth and formed prominent diverging rays, like those on the shells of the proper Mediterranean oyster. The same individual shell, showing both forms of growth, was exhibited before a society in Paris. Lastly, it is well known that caterpillars fed on different food sometimes either themselves acquire a different colour or produce moths differing in colour. (23/44. See an account of Mr. Gregson's experiments on the Abraxus grossulariata 'Proc. Entomolog. Soc.' January 6, 1862: these experiments have been confirmed by Mr. Greening in 'Proc. of the Northern Entomolog. Soc.' July 28, 1862. For the effects of food on caterpillars see a curious account by M. Michely in 'Bull. De La Soc. Imp. d'Acclimat.' tome 8 page 563. For analogous facts from Dahlbom on Hymenoptera see Westwood 'Modern Class. of Insects' volume 2 page 98. See also Dr. L. Moller 'Die Abhangigkeit der Insecten' 1867 s. 70.)