346 



VELUTINTDiE. 



The operculigerous lobe, which in Nat'ica attains such 

 great dimensions and is reflected upon the shell, is in this 

 family developed in common with the lateral and anteal 

 portions of the mantle, so as to be capable of inverting 

 margins of the shell all around, or to be so completely 

 reflected over the entire shell as to make it " internal " 

 instead of external. The mcntum no longer plays that 

 important jmrt which it has in the Naticidft. The 

 head is flanked by simple tentacula, bearing the eyes 

 on bulgings at their external bases. The proboscis is 

 completely retractile. The lingual teeth appear (accord- 

 ing to Loven) to vary in number, but are always arranged 

 in a single axile series flanked by from one to three 

 laterals. There are two branchial plumes. The shell 

 is always auriform, and is sometimes covered with an 

 epidermis. Its orifice is always patulous and entire. 



VELUTINA. Fleming. 



Shell thin, more or less coriaceous, invested with an 

 epidermis; volutions few, spire short, body whorl vcn- 

 tricose, very large, with an entire patulous aperture : outer 

 lip sharp, peritreme continuous. No operculum. 



Animal bulky, head short, broad, bearing two rather 

 obtuse subulate tentacula, separated at their bases by the 



