j\ecklace-s hells and Winkles 



13 



Head of Wentletrap 



mollusks by reason of tlie ridges that regularly era9,§ 



eacli whorl. The almost round mouth has a flat, 



projecting, and continuous lip. As in many other 



shells, the stages of growtli are indicated by the lips 



successively formed standing up as ridges, but in few 



cases do they stand out so prominently 



as in this genus. The mouth is closed 



by a horny ear - shaped operculum. 



The head of the animal is short, but 



provided with a retractile proboscis of 



a cylindrical shape. The tentacles are 



awl-shaped, and at the outer side of their bases the 



eyes ai-e situated on short stalks. Like lanthhia 



the Wentletrap animal ejects a purple fluid when 



molested. 



Turton's Wentletrap (*S'. tuTtonre) is rather glossy, 

 and consists of about 15 whorls, crossed by slightly 

 curved and flattened ridges, of which there 

 are 12 on the largest whorl. The colour 

 is light yellowish brown with three spiral 

 bands of purple-brown, the lowest of which 

 is visible only on the last whorl ; operculum 

 dark brown. The length of the shell is 

 an inch and three-quarters, and it is half 

 an inch across at the base. It is by no 

 means a common shell, but it may be found 

 along the coralline zone on many parts of 

 our coasts. The Common Wentletrap (S. 

 communis) is similar to the last, but the ridges are 

 merely folded back, not flattened, and there are only 

 9 on the body whorl ; they are also connected from 

 whorl to whorl, so that they form continuous but 

 oblique lines from the apex to the base. The spiral 



