296 trochiDjE. 



inclined to be angular above : outer lip plain in the female, 

 and spread outwards in the male : inner Up folded back a 

 little on the umbilical cavity : umbilicus narrow but deep, 

 exposing the base of the penultimate whorl : inside iridescent : 

 operculum having about a dozen volutions, becoming slightly 

 concave towards the centre ; the nucleus forms a boss or pro- 

 jecting point on the under side. L. 0425. B. 0*25. 



Yar. fasciata. Smaller, light-yellowish or creamcolour, 

 with a spiral band of reddish-brown between the suture of 

 the last whorl and the periphery. 



Habitat : Abundant on the fronds of Laminaria 

 saccharina, and under loose stones, throughout the 

 laminarian and lower part of the littoral zones, in Shet- 

 land, the Orkneys, both sides of Scotland, and the coasts 

 of Berwickshire, Northumberland, Durham, and York- 

 shire ; Belfast (Hyndman); Dublin Bay (Warren and 

 Kinahan) ; and Connemara (Farren). Brown says 

 " also on the south coast of Devonshire," and Leach 

 endorsed the statement; but this must have been a 

 mistake. The variety was found by Mr. Bean at 

 Scarborough, by Mr. Hyndman in the north of Ireland, 

 and by myself in the west of Scotland. T. helicinus 

 is fossil at Fort William (J. G. J.); Oban (Geikie); 

 Clyde beds (Crosskey); and at Uddevalla. It inhabits 

 the shores of Scandinavia, Iceland, Spitzbergen, the 

 White Sea, Sea of Okhotsk, Greenland, Behring's Straits, 

 Labrador, Canada, and the north-eastern coasts of the 

 United States, at depths ranging from low-water mark 

 to 40 f. 



The animal is active and bold. It appears fond of 

 crawling out of water. When floating with the shell 

 downward, the tongue is seen to be continually pro- 

 truded, as if in search of some microscopic food. The 

 gill is visible through the opening on the left-hand side 

 of the head, and resembles a miniature Plumularia fal~ 



