RISSOA. 99 



be a smooth, produced, and, for the most part, immature 

 variety of this polymorphous shell, we only adopt an idea 

 which those veterans in British couchology, Messrs. Jef- 

 freys and Clark have entertained for many years, and which, 

 although it may seem unlikely to those whose examples 

 of either form have been selected as intensely characteristic, 

 yet will, we feel assured, be ultimately assented to by all 

 who study like ourselves, from multitudes of specimens, 

 gathered from far apart localities. 



Ordinary specimens of the ribbed or more character- 

 istic variety are moderately strong, glossy, scarcely at 

 all translucent, and of an ovate-conic shape. They dis- 

 play much diversity of colouring, some individuals being 

 wholly squalid white, whilst others are encircled with 

 so broad a band of dark brown, chestnut or fulvous 

 brown on the upper and lower portions of their prin- 

 cipal or larger whorls, as only to exhibit a narrow in- 

 tervening strip of white in the middle of their volutions. 

 Sometimes the dark hue may actually be regarded as the 

 ground colour, the pale strip being confined to the last 

 two coils. The labial varix is white, and the extreme 

 base of the body whorl, as well as the raised sculpture, 

 is usually a shade or two lighter than the general tint, the 

 prominent ribs being oftentimes nearly white throughout 

 their entire length. These last range from eight to twelve 

 upon the body whorl ; the lesser number when they are 

 solid and broad, the larger number when, as is sometimes, 

 but not ordinarily the case, they are narrow ; their intervals 

 are broader than the costa) themselves, and are sometimes 

 smooth, sometimes spirally striolate. In characteristic 

 examples the early turns are destitute of sculpture, the 

 ribs being confined to the penult and antepenult turns, 

 and to the upper two-thirds of the body whorl, at the 



