428 BULLID.E. 



equally broad at each end ; it is quite transparent and lustrous : 

 sculpture, very slight and indistinct spiral lines (perceptible 

 towards the spire only) and the usual marks of growth : epi- 

 dermis inconspicuous : colour clear white, except the nucleus 

 or embryonic whorl which is brownish -yellow : sjpire abruptly 

 truncated : ivJiorls 3— i, angulated at the top ; the first is oval, 

 twisted inwards, and slightly prominent: suture deep and 

 channelled : mouth rather narrow on the upper part and very 

 wide below ; in full-grown specimens it never extends to the 

 spire, and is shorter than in the last species ; base expanding 

 and obliquely rounded : outer lip flexuous, contracted and in- 

 flected at about one-third of its length from the top ; outer 

 corner bluntly angular ; inner corner considerably receding 

 and incurved : inner lip folded over the pillar, elsewhere want- 

 ing : piUar short, almost straight above, and curved below : 

 fold obscure: umbilicus distinct and deep, although small. 

 L. 0-2. B. 0-125. 



Habitat : Living in the laminarian zone, on various 

 parts of the British coast, and dead in deeper water. I 

 will mention a few localities (out of about thirty which 

 I have noted), to show the extent of distribution; — 

 Guernsey, Cornwall, Dorset, South Devon, South Wales, 

 Donegal, Galway, Cork, Dublin, west and east of Scot- 

 land, Shetland, and the north of England. Fossil at 

 Dalmuir (Crosskey and Robertson) ; post-glacial bed 

 in Norway, 50 feet (Sars) ; Sparebakken near Christi- 

 ania (Robertson) . Its existing range abroad comprises 

 Kiel Bay (Meyer and Mobius), Sweden (Loven and 

 Malm) , Norway (Danielssen and others) , Iceland (ToreU), 

 Greenland (Moller and others) , Massachusetts (Goidd), 

 New England (Stimpson), Madeira and Canaries (M^An- 

 drew) ; depths 10-60 f. 



The animal differs from that of U. expansiis in having 

 eyes, and in the extremity of the foot being unevenly 

 lobed or heterocercal ; the shell may be distinguished by 

 its smaller size, want of angularity in the middle, and 

 by its larger and more conspicuous umbilicus. 



I 



