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NATICIDiE. 



In this family we have an assemblage of Gasteropoda 

 presenting very peculiar and marked characters. The 

 shell is spiral and more or less globular or expanded, 

 usually smooth and polished. Its general aspect resembles 

 that of Nerita, so that for a long time these two very dis- 

 similar mollusks, so far as essential characters of organiza- 

 tion go, were placed in one family and originally in one 

 genus. The animal of the Naticida has, however, a re- 

 tractile proboscis, and is remarkable for the great develop- 

 ment of the fold or mentum on the upper and anterior 

 portion of the foot, which becomes in it a great lobe re- 

 flexed upon and protecting the head. The operculigerous 

 lobe is also remarkably developed and reflected upon the 

 shell. The tongue is furnished with teeth. The Katicidoi 

 appear to be of exceedingly predacious habits. They are 

 chiefly inhabitants of the laminarian and coralline zones. 

 There are numerous and beautiful forms of the tribe in 

 tropical seas. 



From the earliest geological epochs there appears to 

 have been well marked members of this family inhabiting 

 the area of the British seas. Some of these, even among 

 the most ancient, bear a striking resemblance to existing 

 species, but, not until the later tertiary epochs do we find 

 British Naticidee. identical with those now living. 



