STRUTHIOLARIA. 



minea^ or nodulosa, by its smaller size*, and its wanting the 

 rather pointed tubercles that surround the upper part of the 

 volutions of S. straminea : its less sinuous outer lip, the 

 greater depth of the spiral line, and the less angular upper 

 part of the outer lip, also distinguish it. 



The animal of this Genus is unknown : whether in its 

 natural state the shell be covered with an epidermis or not, 

 or whether it have an operculum we are unable to tell. 



Not known in a fossil state. 



Fig. 1 and 2. Str. straminea. 

 3 and 4. — — inermis. 



* It may here be observed, that the comparative size capnot, in many 

 cases, be considered as a good specific character ; for we know that shells 

 vary very much in size, even when full grown: here we think it may, for it 

 is evident that the shells of this Genus do not complete the lip, nor form any 

 varicose suture until the time of their adult state; consequently the smaller 

 one cannot be taken for a young specimen, because it has already completed 

 its sinuated revolute lip : and it has other distinguishing characters 



