422 BULLION. 



these are often sharp at the apex, not so distinct in the middle 

 of the shell, and usually disappear towards the base, where 

 they are replaced by lines of growth ; the spire is frequently 

 striated across, like an Ammonite : epidermis filmy : colour 

 white : spire involute, abruptly truncated, and encircled by a 

 narrow and solid rim or rounded keel : whorls 3-4, gradually 

 decreasing in size towards the centre of the apex ; the first or 

 innermost whorl is globular : suture deep : mouth narrow for 

 more than half its length on the upper part, pear-shaped and 

 very wide at the base, which is rounded : outer lip gently 

 curved, and folded inwards in the middle; the upper part 

 projects (sometimes considerably) beyond the apex ; outer 

 corner rounded ; inner corner receding and obliquely incurved : 

 inner lip slight, continuous with the outer lip above, where it 

 is folded a little over the apex, as well as over the pillar, be- 

 hind which it forms a small and narrow umbilical chink : 

 pillar short, thick, and flattened : fold tooth-like and strong. 

 L. 0-175. B. 0-075. 



Var. pellucida. Smaller, shorter, thinner, more transparent, 

 and less strongly ribbed (sometimes quite smooth) ; epidermis 

 slightly prismatic. Volvaria pellucida, Brown, 111. p. 4, pi. 

 xix. f. 45, 46. 



Habitat : Everywhere (chiefly in the laminarian 

 zone) on muddy ground and at the base of seaweeds, 

 from low-water mark to 15 f. The variety appears to 

 be northern, having been noticed by Brown from Dun- 

 bar, and found at Aberdeen by Macgillivray, and in 

 Shetland by myself. This species occurs in the Coral- 

 line Crag (Wood) ; post-glacial beds, Norway, 0-100 

 feet (Sars)j Courtagnon (Bruguiere); Italian tertiaries 

 (Brocchi and others) ; Vienna basin (Homes). It 

 ranges from Oxfjord in Finmark (Sars) to the Canary 

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

 Adriatic, and iEgean ; depths 4-100 f. 



Rather active and fond of floating with its shell down- 

 wards. Professor Loven having informed me that it 

 possesses an operculum, I carefully dissected and exa- 

 mined several live specimens, but I could not detect 



