176 THE CANADIAN NATURALIST. [June 



The arenaceous forms, witli the exception of those which are 

 tubular, constitute a series parallel to the calcareous forms, and 

 the members of which graduate into one another. It seems not 

 improbable that the individuals of the same species may assume 

 either appearance. It does not appear, however, that the same 

 individual can present both forms at successive periods. On the 

 other hand, the sandy forms may really constitute a distinct 

 group parallel to the others. Sketches of some interesting forms 

 are given which do not appear to be precisely similar to described 

 species. These have been kindly examined by Dr. Parker, of 

 London, who regards the Lituolte represented in figs. 1 and 3 as 

 new species, to which he assigns the names L. Jindens and L. 

 cassis. The form represented in fig. 2 he regards as the type of 

 a new genus, to which, from the horse-shoe shaped form of the 

 aperture, he gives the name Ilippocreplna^ naming the species 

 H. indivisa. 



