2o6 Shell Life 



Tlie ground colour is pale yellow, almost covered by 

 short streaks of red and purple. Umbilicus wide and 

 very deep, bordered by a smooth broad ridge. It 

 is a species of our southern and western shores, to 

 which may be added Ireland, Man, the Channel 

 Islands, the Orkneys, and Shetland. It affects a 

 sandy bottom between low-water mark and 40 fathoms. 

 Its vacated shell is a favourite cell for Prideaux's 

 Hermit-crab, which has for companion an anemone, 

 the Cloaklet, that wraps the shell completely round, 

 and by secretions from its under-surface dissolves 

 out the mineral portions and leaves only a soft 

 mass resembling sodden paper more than shell. 



The Pearly Top-shell {T. cinctuft); this and the 

 two following species are characterised by their 

 pearl}^ lustre, and their possession of an umbilicus. 

 The shell of the present species is pyramidal, semi- 

 transparent, pure white with a pearly iridescence. 

 The largest whorl has two large and several smaller 

 ridges, some of wliich are continued along the other 

 6 whorls. The mouth would be circular but for 

 its interruption by the spiral ridge which encircles 

 the deep umbilicus. It is a small species, its height 

 being one-third of an inch and its breadth a little 

 less. It was first found by Mr. J. G. Jeffreys in 

 1861, who dredged it on fine sand and gravel in 

 85 to 95 fathoms, about 25 miles north-north-west 

 of Burra Firth Lighthouse, Unst. 



The Greenland Top-shell {T. groemlandicus) is 

 rather rotund and solid, slightly glossy, with fine 

 spiral ribs. There are 6 whorls, and the upper 

 part of each is puckered up irregularly. The colour 

 is a flesh tint, without streaks or spots. The um- 



