196 



NATURAL HISTORY. 



it is like a land-shell of the genus Achatiiia, the shell being ventricose, and smooth, the apex regular 

 and obtuse. 



Notwithstanding the fact that the fossil species of this rare and interesting shell had been found 

 in true marine deposits in Italy associated with sea-shells, and sometimes coated by a coralline 

 (Lepralid), yet Dr. Gray for many years adhered to the opinion that Halia was a true Land Snail, and 

 placed it as such in the British Museum shell-collection. At length Mr. 11. D. Dai'bishire, of Man- 

 chester, having learnt that the specimens hitherto sold had been certainly obtained at Cadiz, set out 

 for Spain, and, by showing a shell (which he carried with him for the purpose) to the fishermen on 



GROUP OF SEA SNAILS 1, PATELLA VULGATA ; 2, BUCCINUM TJNDATUM ; 3, NASSA RETICULATA ; 

 4, HALIOTIS TUBERCULATA ; 5, LITTORINA LITTOREA. 



the coast, was rewarded by obtaining several living specimens from deep water off the lighthouse, 

 Cadiz, thus proving the correctness of the evidence derived from the fossil shells from Italy. 



The genus Eburna (ebur, ivory), or " the Ivory-shell," is a thick, solid, smooth shell, with a short 

 spire, umbilicated when young, but the umbilicus is covered by the callus of the inner lip in 

 the adult. These shells have usually lost their epidermis, and are then pure white, spotted with 

 dark-red ; the animal's body is also spotted like the shell. Nine species are known from the Red Sea, 

 India, and China. It extends also to Australia and the Cape. 



The " Dog Whelk" (Nassa*) has a shell like Buccinum, but is much smaller ; the columellar lip 

 is thickened by a callus, and expanded, so as to form a tooth-like projection near the anterior canal. 

 The animal has a broad foot with diverging horns in front, and two little tails behind. Nfiaaa 

 reticulata is common on the English shores at low water, and is called the " Dog Whelk " by fisher- 



* Nassa, a basket used for catching fish. 



