RANELLA. 



however, only observe, that it does not appear in the 

 slightest degree probable, much less necessary, in order 

 to account for the particular form of these shells, that 

 the animal should adopt a different mode of constructing 

 its habitation from that adopted by all other animals of 

 the same class ; which, it is well known, is by depositing 

 from their mantles successive layers of testaceous matter 

 around the edge of their apertures, without being obliged 

 to expose themselves to unnecessary danger by coming 

 out, and remaining until an entire half volution has been 

 formed. 



The Ranella are generally ovate, sometimes oblong, 

 (and in the oblong species, the varices are not so regu- 

 larly distichous as in the ovate,) very slightly depressed 

 in reality, yet having the appearance of being peculiarly 

 so, on account of the breadth of the varices ; which form 

 in general a regular row on each side, more or less ob- 

 liquely placed. On the outside, the Ranellae are always 

 covered more or less closely with tubercles and rows of 

 small beads, and the varices are sometimes, but not often, 

 . spinous. Specimens are very seldom brought to this 

 country with their epidermis, but such as have any re- 

 mains of it, prove it to be a thickish olivaceous coat. 

 Their aperture is rather ovate, with a more or less length- 

 ened canal at its base, and frequently also at its superior 

 extremity ; the inner lip is mostly rugose, and the inside 

 of the outer lip grooved, and its edge crenatcd or den- 

 tated. We have never seen its operculum. 



The Raneilse are marine: the species are not very 

 numerous, most of them are inhabitants of the East Indian 

 Seas. There are very few fossil species those that we 

 have seen are found in the London Clay. 



Fig. 1. Ranella candisatn, \jKm. Murex candisatus, Chemn. Murex conditusy 

 Gmel. A very scarce and valuable shell from New Guinea ; for the loan of 

 which we are indebted to Tliomas Johnstone, Esq. 



2. spinostty Lam. 



3. marginata. JBuccinum marginatum , Gmel. Ranella Icevigatay 



Lam. A fossil species from Piacenza : the»e is a recent shell very nearly re- 

 .serablin^ this. 



