order trachelipoda. 31 



Family COLUMELLARIA. 



This family is distinguished from the next in having 

 the columella plaited, and a notch at its hase. It does 

 not include any shells with a plaited columella, the open- 

 ing at the base being entirely smooth, that is, without a 

 notch.' 



The Diadem Whorl Shell, {Valuta diadema.) 



The Diadem Whorl Shell is a very beautiful specimen of 

 its genus; it is marbled with white upon a yellow ground, 

 but the markings become nearly obliterated by age: it is 

 as much as seven inches in length, and is found in the 

 Asiatic seas. The head of the animal of this shell has 

 two pointed tentacula?, with an eye at the outer base of 

 each. Its mouth is a lengthened cylindrical and retrac- 

 tile tube, furnished with little hooked teeth ; it has also 

 a tube to conduct the water to the branchise, springing 

 out obliquely behind the head. 



The Common Columbella, (Columbella mercatoria.) 



The common Columbella is found in the Atlantic Ocean 

 near the island of Goree, and in the West India 

 Islands ; it is about three quarters of an inch in length. 

 It is a sea-shell, and is found upon the coast ; it pos 

 sesses a very small oval operculum attached to its foot. 



Family PURPURIFERA. 



The notch at the base of the shells of this family is a 

 kind of groove bent backwards and upwards, but not 

 properly forming a canal : all the genera have an oper- 

 culum. The name Purpurifera has been given to these 

 Trachelipodes, because some of the genera contain in a 



