152 HELICHXE. 



composed of six or seven raised volutions, slightly 

 striate longitudinally ; aperture oblong-oval, with 

 the margin white and reflected, forming a slight um- 

 bilicus behind the pillar. The young shell conical, 

 pyramidal, with a subquadrangular mouth. 



It scarcely differs, except in size, from the last 

 species ; but it is of a paler brown, with the volu- 

 tions more rounded, and the peristome is white. 



Varies like the last, and being more common, the 

 varieties are more often observed. 



The jaw of B. montanus and It. obscurus is lunate, 

 rather narrow, crenated on the edge. 



The Rev. Mr. Sheppard remarks, " These shells, 

 particularly in their young state, show great sagacity 

 and ingenuity, by covering themselves with a coat 

 adapted to the different situations in which they are 

 found ; and when so covered, it is almost impossible 

 for any other than a conchological eye to discover 

 them. If its abode be upon the trunk of a tree 

 covered with lichen, then is the epidermis so con- 

 structed as to cause the shell to resemble a little knot 

 on the bark covered with such substance. If on a 

 smooth tree, from whose bark issue small sessile buds, 

 as is frequently the case, it will pass off very well 

 for one of them ; and on a dry bank, or the lower 

 part of the body of a tree splashed with mud, its 

 appearance will be that of a misshapen pointed piece 

 of dirt." (Linn. Trans, xvi. 166.) 



b. Shell turreted, white, banded, covered with a thin 

 periostracum ; whorls rapidly and regularly en- 

 larging ; mouth small; peristome thin, scarcely 



