li 



wliether it is adult. The signs of juvenility are — 

 sharp extremities, thin texture, imrtl(^ularly the 

 outer Hp, which is frequentty, on this account, 

 broken, the very light color in the quite young and 

 the absence of callosity upon the columella. 



A comparison of shape, angle of divergence of 

 the whorls, etc., with specimens of adult shells, or 

 with figures and descriptions, will generally suffice 

 to detect half-grown shells. 



Many of the ponderous Alabama Goniohases are 

 hidbous in the half-grown state ; the spire at first 

 narrowly acuminate, then suddenly and very con- 

 vexly expanding, resembling the growth of certain 

 West India CylindreUce. As with these terrestrials, 

 the subulate portion invariably disappears in the 

 adult, leaving a somewhat pup^eform shell. 



We thus find that no one character (with very 

 few exceptions) can be relied on in specific discrim- 

 ination ; but rather a comhiiiation of characters, with 

 a general idea of the necessary allowance for varia- 

 tion pervading other species of the same general 

 tj-pe, or contiguous locality. 



