128 PYRAMIDELLIDiE. 



are often visible outside : inner lip adhering to the pillar above 

 the tooth, and joining the outer lip at its upper angle, reflected 

 and curved below the tooth : umbilicus small but deep, partly 

 covered by the reflexion of the inner lip : tooth strong, promi- 

 nent and conspicuous, placed just behind the umbilicus ; it 

 winds round the pillar from one end of the spire to the other, 

 like the worm of a corkscrew : operculum yellowish-brown, of 

 equal proportionate solidity with that of Cychstoma eler/am, 

 and exquisitely sculptured by close- set flexuous strise in the 

 line of growth ; it has a curved groove down the middle, which 

 ends in the spire of the operculum, and gives to the portion 

 thus separated in front a cornucopia-shape ; this groove is 

 deep and very distinct ; side-flap rather broad, widening with 

 the growth of the operculum, and divided from the spiral part 

 bv a narrow line. L. 0*25. B. 0*1. 



a/ 



Var. australis. Smaller and narrower. 



Habitat : Coralline and deep-sea zones, in mud, from 

 25 to 80 f., throughout Shetland and Scotland; Isle of 

 Man (Forbes, as 0. plicata apparently) . It is locally 

 plentiful in the Clyde district and Hebrides. The variety 

 lias a southern range, comprising the Channel Isles, 

 Dorset, Devon, Cornwall, Galway, and Cork ; in rock- 

 pools, Falmouth (Barlee, and Miss Vignrs, fide Cocks) ; 

 among Zoster a, Jersey (Dodd). This species was ori- 

 ginally described as a fossil by Brocchi from the Sub- 

 apennine tertiaries, and it has been recorded by Philippi 

 from basaltic tufa at Militello, by Nyst (as 0. plicata) 

 from Belgium; and by Searles Wood (under the latter 

 name) from our Coralline Crag ; the Rev. H. W. Cross- 

 key has found it in the Clyde beds, and M. Mace in an 

 upper miocene deposit near Antibes. The ordinary or 

 typical form inhabits the North Sea, from Hammerfest, 

 40 f. (Sars), to Gottenburg, 12 f. (Malm); and the variety 

 is distributed along the European coasts of the Atlantic 

 from Brittany, in the laminarian zone (Cailliand), to 

 Gibraltar, 8-30 f. (M f Andrew), every part of the Medi- 



