"Top-shells and Pheasant-shell 207 



bilicus is narrow, but very deep. It is a quarter 

 of an inch across and a little less in height. Its 

 British distribution is limited to the west of 

 Scotland, Shetland, and the Orkneys, where it occurs 

 on rocks about the base of the Laminarias, from 

 low water to a depth of 40 fathoms. 



The Small Pearly Top-shell {T. helicmus) is less 

 conical and shorter than the last, less solid, semi- 

 transparent, and highly polished. There are no 

 ribs, and the siitwre or hollow line that separates 

 the 5 whorls is less deep than in the last. The 

 umbilicus is also less deep. The colour is orange 

 varying to reddish brown, occasionally tinged on the 

 upper-side of the whorls with blue or purple. It 

 is a quarter of an inch across the base, which is 

 almost twice the height. Its habit is similar to 

 that of the Greenland Top, but its habitat must 

 be extended by the addition of the east coast 

 of Scotland and its continuation as far south 

 as Yorkshire; also Belfast, Dublin Bay, and 

 Connemara. 



■ The Pheasant-shell (Pkasianella imlliis) belongs 

 to a family {Tnrhinidw) distinct from the Top- 

 shells, and this is its solitary repre- 

 sentative in this part of the world. 

 The home of the genus Phasia- 



nella is in Australia, where the ^^ ^ 



shells are large, — P. australis is pheasant-sheii (enlarged) 

 2 inches long and 1 inch across, 



in the Philippines and India they are much 



smaller, whilst in the Mediterranean, the British 

 seas, and the West Indies they have dwindled to 

 very small examples. Our own species is no more 

 14 



