NATICA. 331 



somewhat produced : yet it only occupies two-sevenths of 

 the dorsal length. The more characteristic specimens 

 (especially the younger ones) are encircled with five mode- 

 rately distant bands of short angular or flexuous purplish 

 brown streaks, of which the three lower series are sagit- 

 tate, and the two upper, the second of which is broader 

 than the rest, and the first of which is continued along the 

 two or three next turns, composed of letter-like markings or 

 oblique and irregular wavy lines. The ground-colour of the 

 smooth and highly-polished exterior ranges in tint from 

 creamy white or very pale fawn to livid or chestnut ; 

 sometimes, indeed (and chiefly in the more aged examples) 

 this last colour entirely obscures all but the subsutural 

 streaks ; and sometimes the shell is almost wholly devoid 

 of colouring, yet vestiges of the bands are usually to be 

 traced by those who look for them. The body is very 

 large, moderately ventricose, more rounded below, where 

 its declination is moderatel}^ sudden, tlian it is above, 

 where it shelves considerably, and is slightly flattened, or 

 is occasionally even in some slight measure retuse. The 

 spire is composed of five, or five and a half coils, whose 

 volutional increase, especially that of the penult, which 

 becomes abruptly higher than the preceding turn, is more 

 or less rapid. They shelve into each other, from the 

 quickness with which they taper above, which diminishes 

 their appearance of convexity, so gently, that the fine and 

 oblique suture (which is never margined with white) seems 

 but slightly impressed ; the apex is small and not much 

 projecting. The mouth fills about two-thirds of the ventral 

 length, and is of a nearly oval figure, that is rather more 

 broadly rounded below than above : its basal recedence (on 

 which depends the angle of the spire's elevation) is mode- 

 rate ; the throat is smooth, and usually nearly white. 



