328 MURICIDiE. 



shells, usually dexlral, that have been noticed as hete- 

 rostrophe, and 5 sinistral species of which orthostrophe 

 specimens have been discovered. I have been able to add 

 a few more examples from our own fauna. Conditions of 

 habitability (such as the depth and mineral ingredients 

 of water, the soil, food, and climate) do not afford any 

 clue to the solution of the problem ; for the normal and 

 abnormal forms live together. Nor, if such be the 

 agents, can we tell 



" Why all these things change, from their ordinance, 

 Their natures and preformed faculties 

 To monstrous quality." 



This is the u whelke " (par eminence) of Lister, and 

 Buccinum magnum of Da Costa. Pennant and others 

 of the old English school of conchology mistook it for 

 the Miirex despectus of Linne \ the fry is M. decollates 

 of Pennant, but not of Gmelin. The Tritonium anti- 

 quum of Eabricius is F. Islandicus. Bolten founded his 

 genus Neptunea, and Swainson his genus Chrysodomus 

 on the present species. 



F. despectus is an arctic species, having a bathyme- 

 trical range of 8-160 f. ; its southern limit is Christian- 

 sund, in lat. 63° 7'. I procured two live specimens in 

 the Billingsgate market, mixed with F. antiquus. It 

 seems that a vessel sailed from Hull for the long-line 

 fishery at Iceland, and took a quantity of our common 

 whelks as bait ; that when the supply was exhausted, 

 the fishermen used refuse portions of fish to catch fresh 

 whelk3 on the spot ; and that, on bringing their cargo 

 of fish to England, some of the Iceland whelks that 

 remained found their way into the London fish-market. 

 This is one way of accounting for the casual introduction 

 of foreign species into the British fauna. F. despectus 

 is mentioned by Mr. S.Wood (as a carinated variety of 



