234 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



now exhibit are due merely to convergence, and are not real. To sum 

 up : It appears that a number of forms, such as Typholia, Bythoceras, 

 JVassopsis, and Melanopsis, must unquestionably be excluded from the 

 Melaniidse, if that family is to be represented by the Ilelania amarula 

 type, and they will have either to be incorporated into other totally 

 distinct families or formed into new ones. It also seems that those 

 forms which remain can be split up into the Littorino- and Ceritho- 

 Melanias respectively, and that neither of these groups bears any near 

 morphological relationship to the other. 



Lastly, Bouvier, as noted, has already reduced the distinction between 

 the Ceritho-Melanias and the Cerithiidse to a vanishing point, by 

 showing that apart from the characters of their shells the members 

 of these families are not capable of being morphologically distinguished 

 from each other. Family distinctions are, however, generally far greater 

 than this even among the Prosobranchia, and it is only logical, there- 

 fore, that the Ceritho-Melanias, with their type, Melanin amarula, 

 should be bodily transferred to the Cerithiidae as simply the fresh- 

 water contingent of that family. 



This would necessitate the creation of a new family name for the 

 littorinoid forms, if further investigation does not show, as it possibly 

 will, that they must be transferred bodily to the Littorinidse. 



