TURBO TURBAN SHELL. 103 



craggy shores, or on the sand, when detached by 

 a storm from their customary abode. 



There is no indication in the shells of either 

 genus of an increase in growth after the first 

 formation. There are several species of Needle 

 or Screw-shells among the Turbines ; they are 

 distinguished by their circular mouth, from those 

 of a similar form in other genera ; their shape is 

 that of a well-proportioned spire, formed by 

 thirty or forty whorls, gradually tapering from the 

 base to the apex, and terminating in a fine point. 

 There are upwards of seventy species of this 

 genus among British shells, and several of them 

 are terrestrial. One called Turbo* Fasciatus, is 

 found so abundantly in a part of Cornwall, that 

 it is impossible to take a step without crushing 

 numbers. It is the prevailing opinion, that they 

 contribute much to fatten sheep ; they spread 

 themselves over the plain and hill near Whitsand 

 Bay, Cornwall, and the sheep which browse on 

 the short herbage, must devour a prodigious 

 quantity of these mollusca, which early in the 

 morning ascend the short blades in quest of 

 their own food. Some very small Turbines, are 

 found abundantly on old walls amidst moss. 



* Turbo, the Latin for a whirlwind ; trochus, a top. 



