CERITHIUM. 263 



from Brittany (Cailliaud) to Madeira and the Canary- 

 Isles (M'^Andrew)^ and throughout the Mediterranean, 

 Adriatic, and ^gean (shore to 69 f.) ; that of the smaller, 

 which is our form, is more extensive (shore to 100 f.), 

 and comprises also the Scandinavian coast from Chris- 

 tiansund (Danielssen) and Bohuslan (Loven and Malm) 

 to Hsellebsek in Zealand (mus. Copenh.) . West coast 

 of North America (Coo^per, fide P. Carpenter). 



The shell is never varicose. Linne noticed that in 

 this species also there is no canal as there is in Buc- 

 cinum. 



I can see no other difference than that of size between 

 Mediterranean and British specimens, said to belong to 

 two species, viz. C. perversum and C. adversum. They 

 agree in shape, sculpture, colour, form of the mouth, 

 and all other particulars. The greater size of the former 

 shows a deviation from the general rule ; the same ex- 

 ception appears in C. reticulatum also. It must be 

 observed, however, that size is an extremely variable 

 character in the genus Cerithium and its allies. I have 

 specimens of C. reticulatum and of the present species 

 from the south of Europe smaller than any from the 

 north. The only distinction pointed out by the authors 

 of the ' British Mollusca ^ between C. perversum and C. 

 adversum is that the latter is " far scarcer and less dif- 

 fused.^^ Besides the name (Murex adversum) given by 

 Montagu, this shell has 1 1 others, which my readers will 

 not thank me for specifying. It is almost time that the 

 tedious and useless practice of repeating obsolete syno- 

 nyms should cease. 



The " large, subpellucid, white variety " of the last 

 species, noticed by Montagu on Bryer's authority from 

 Weymouth, and on Laskey^s authority as Scotch, is 

 West-Indian. C. cancellatum of Brown (having four 



