182 SPECIFIC 



PLATE XXIV. 



This plate is intended to point out to beginners 

 in Conchology the great diiference which exists, in 

 certain species, between the shell in its young, un- 

 finished state and the same arrived at its perfec- 

 tion. The examples adduced are among the most 

 conspicuous, but there are many others of which 

 it would be very beneficial to students to acquire 

 an early knowledge. 



The mature specimen of BuccinumFiZ'ea; isgiven 

 in Plate XXI. fig. 3. 



PLATE XXV. 



Sections of the several genera are here offered 

 rather as subjects of curiosity than as necessary to 

 the science. They, however, show more accu- 

 rately the true form of the inner chamber than even 

 the aperture itself, which is often altered by the 

 expansion or contraction of the margin, and 

 is generallv oblique to the direction of the whorls. 

 The sections of Nautilus and Turbo constitute the 

 two explanatory figures at the top of Plate I. 



