198 CERlTHIADiE. 



It ranges from Norway to the Mediterranean, and was 

 present in our area during the coralline crag epoch (Searles 

 Wood).-"- 



0. METULA, Loven. 



Pure white ; whorls witli three spiral granulated ridges, whose 

 intervals are more or less distinctly clathrateJ. 



Plate XCI. fig. 3, 4. 



Cerithium metula, Loven, Index Moll. Scandinav, {184G), p. 23. 



„ nitidum, Forbes, Ann. Nat. Hist. vol. xix. (1847), p. 97, pi. 9, f. -. 



This interesting and rare shell was discovered about the 

 same time in England and Norway. It is subulate, thin, 

 and of a pure and uniform subvitreous white. There are 

 from twelve to sixteen short volutions (more frequently 

 thirteen), of which the apical coil and a half are smooth 

 and bulbous. The next few turns are moderately rounded, 

 and the rest quite flat ; their lateral enlargement is mode- 

 rate, their longitudinal increase is slow. The apex is fine, 

 but is twisted to one side, so as to appear distorted and 

 laterally subspiral. Three spiral ridges, which are rendered 



* A shell is figured in Brown's " Illustrations" (pi. 5, f. ti4) which in shape 

 and look exactly resembles a worn aged shell of the present species, but is thus 

 described (p. 9). 



C. cancellatum. Brown, " With eleven reversed, slightly defined volutions, ta- 

 pering from the base to an obtuse apex ; each volution provided with four rows 

 of spiral, depressed tubercles, producing a fine cancellated appearance. These tu- 

 bercles do not extend lower down than the upper margin of the aperture in front, 

 and in a spirally parallel direction behind; aperture triangular, pointed beneath, 

 ending in a compressed, closed, short canal ; colour raw umber brown. Found on 

 the Northumberland coast at Holy Island." If not an adversum, this is probably 

 an exotic shell; neither Mr. Alder (whose list of Northumbrian Mollusks is a 

 valuable contribution to Conchology, and not a mere local catalogue of species) nor 

 any of our many correspondents are acquainted with it. The C. minutissimum of 

 Brown (111. Con. p. 9) is solely derived from the Mureuc minutissimus of Adams 

 (Trans. Linn. Soc. vol. iii. p. 65 ; from which, Mont. T. B. p. 273 ; Maton and 

 Rack. Trans. Lin. Soc. vol. viii. p. 149 ; Turt. Conch. Diet. p. 97, &c.) A sliell 

 so meagrely defined that even the genus it belongs to must be purely conjectural. 



