450 BULLION. 



base : outer Up flexuous, slightly indented or concave in the 

 middle ; the top is level with the spire, the shell being placed 

 mouth downwards; inner corner cloven, and producing the 

 same partial disconnexion of the body-whorl as in the last 

 species : inner lip forming a broad and thickened glaze. L. 0'15. 

 B. 0-1. 



Yar. zona. Rather more depressed, with a belt of clear 

 white in the middle, taking in from eight to ten of the chain- 

 like rows. 



HABITAT : Exmouth, alive in rock -pools at the time 

 of the lowest spring tides (Clark ) ; on different parts 

 of the coasts of South Devon, Cornwall, and Dorset 

 (Montagu, Tyacke, fide Forbes's MS., J. G. J., and 

 others) ; Guernsey (Barlee and J. G. J.) ; Tenby (J. 

 Adams and J. G. J.) ; Manorbeer near Tenby, and 

 Langland Bay near Swansea (J. G. J.) ; Scarborougli 

 (Bean and J. G. J.) ; Northumberland (Alder) ; Ber- 

 wick Bay (Johnston) ; Cork (Humphreys, from the 

 stomach of a sole, and J. G. J.) ; Miltown-Malbay, co. 

 Clare (Harvey, fide Thompson) ; Arran Isles, co. Gal- 

 way (Barlee) ; Bundoran, co. Donegal (J. G. J.) ; Dub- 

 lin Bay (Walpole and J. G. J.) ; Lamlash, Isle of Bute 

 (Landsborough) ; Skye (Barlee); Firths of Forth and 

 Clyde (Brown) ; Shetland (Barlee) . The variety is 

 from Bigberry Bay, near Plymouth (Montagu), and 

 Guernsey (coll. Turton and J. G. J.). P. catena occurs 

 in the Coralline Crag at Sutton (Wood, as Bullaea 

 sculpta) ; Palermo (Calcara, as B.punctata). Its extra- 

 British distribution, as a recent species, appears to be 

 southern, and comprises the Loire-Inferieure (Cailliaud), 

 Mediterranean, from the Gulf of Lyons (Martin) td 

 Sicily (Maravigna and Philippi), and^Egean, in 119 f. 

 (Forbes). 



The gizzard resembles that of P. scabra, but is 

 smaller and has a shorter midrib. My largest specimens 



