ON MOLLUSCA. 261 
Flatted when the united whorls form a surface altogether 
flat, as in conus cardinalis. 
Crushed when the progress in a vertical direction is but 
little rapid compared with that in an opposite direction. 
These are the shells which approach a little to those named 
above, discoid ; for example, the solaria. 
Moderate when the progress in both directions is pretty 
nearly equal, as in the buccina, &c. 
Elevate when the spiral cone advances more in height than 
in breadth. 
Elongate when this disposition is still more marked. 
Turreted, or turriculate when with a similar disposition 
the whorls are very exactly separated by their different divi- 
sions of thickness, as in mitra. 
Decollated when in consequence of age their extremity is 
broken. 
Coronate when the edges of each whorl are armed with 
projecting points, with tubercles or spires, as in a great num- 
ber of coni, and in the Ethiopian voluta. 
The whorls, or turns of the spire, also give rise to many 
characters, which are expressed by determinate words. 
As to their number, they are reckoned either in proceeding 
from the summit or from the end of the spiral cone. 
Their proportion one to another is expressed in ordinary 
terms. It often happens that the last whorl but one is bigger 
than the rest altogether; sometimes the last is smaller than 
the last but one, &c. 
The whorls themselves may sometimes be quite flat, to 
which the name of ribboned has been given, as in terebra. 
Sometimes they are distinguished with difficulty, and may be 
considered as almost confounded ; finally, they may be sepa- 
rated from each other by a pretty deep furrow, as in the 
olives: this line of separation between thé whorls is named 
sulure (sutura). 
