114 C O N C H O L O G Y. 



Thefe are the four principal dlfpofitions oi 

 the fpires ; but there are many intermediate 

 ones, which proceed from diiTer.ent degrees 

 and combinations of thefe four. 



The number and forms of the fpires 

 vary in the fame fpecies, either in their 

 different growths or fexes. Young Shells 

 have always a lefs number than the old 

 ones : the reafcn is plain, as all turbinated or 

 Ipiral Shells take their growth from the tip 

 ©r end to the mouth, or upwards. Some 

 Shells, though of the fame age, fometimes 

 have not the fur.e number of fpires : that 

 is to be attributed to ficknefs, or rather it 

 is an effcft of the fex. Thus, in the Pur- 

 purse^, the Buccina, and in fome other kinds^ 

 it is common for the males to have their 

 fpires lefs numerous ;. mare flender and 

 lengthened, or lefs fwelled ; and the whole 

 Shell fmaller, than in the females. This 

 obfervatlon, which I have not neglefted 

 to make whenever opportunity offered, 

 I always found to be conftant. 



Th® 



