CERITIIIUM. 193 



The specific name scahrum, was undoubtedly prior to 

 that of reticulatum, but as Olivi has so wretchedly defined 

 his shell, that it is only the assigned locality which enables 

 us to recognize what he meant, we have preferred the 

 epithet which was first attached to the species described and 

 delineated in such a manner as to secure its recognition. 



Of this shell we have two principal varieties in 

 England, the one subulate and strengthened with lon- 

 gitudinal varices, the other without them, and of a more 

 abbreviated shape. The former has sometimes fourteen 

 whorls, the latter more often only ten. In native ex- 

 amples, the varicose individuals are usually of an uniform 

 chocolate or dark brown colour (pale tawny when dead) ; 

 the other variety more frequently is yellowish-brown, with 

 its raised spiral lines (the nodules excepted) of a rich 

 dark brown hue ; this colouring, however, is frequent in 

 Mediterranean specimens of the former variety. 



The shell is thin, not very strong, tapers from the base 

 to the summit, and is adorned with four spiral rows of 

 granular nodules on each of the principal or lower turns of 

 its spire, which asperities are produced by the intersection 

 of numerous almost perpendicular narrow rib-like folds, 

 which run leng-thwise from the summit to the base of 

 each of these volutions, and revolving and equidistant 

 costellar lines. Of these last, there are about five ad- 

 ditional almost simple ones on the base of the body, where 

 the folds are no longer present. Sometimes the folds, 

 sometimes the costellse, are the more prominent, but the 

 latter are always more closely disposed than the former, 

 which, indeed, on the earlier turns, where there are but 

 three or even two revolving lines, are few and distant. 

 The varices, when present, are at times rare and scat- 

 tered, at times form an almost continuous series opposite 



VOL. 111. c c 



