112 
This varies a little, and is very often like Brander’s 
excellent figure. It is generally very chalky, and seems as 
if it had all the ornaments obliterated or worn, but is not so 
much so as might be supposed, for my specimen had some 
fine Flustra that appeared to be cotemporaneous with it, 
which in a great measure indicates that although somewhat 
worn, it never was very full of ornament, but always nearly 
as represented. 
Most of the species of this Genus are very abundant 
wherever they occur, and every one is liable to vary, 
which makes it difficult to distinguish the species; how 
far I have divided them right can hardly be determined 
till more figures, specimens, and experience gives the 
necessary aid. 
Fig. 7 may possibly be an older shell of the same species 
as fig. 2. 
