814 trochidjE. 



Habitat : Gregarious among stones, and on Fucus 

 serratus, just below the brink of high-water mark at 

 neap tides, on our southern coasts, in the Bristol Chan- 

 nel, Isle of Man, all around Ireland, and west of 

 Scotland as far north as Loch Alsh. The following 

 localities are doubtful : — " North Britain " (Laskey) ; 

 Aberdeenshire, Banff, and Kincardine (Macgilli- 

 vray). The variety atro-purpurea was found by Mr. 

 Clark at Exmouth ; decorata by myself at Wey- 

 mouth ; and Agathensis is not uncommon in the Channel 

 Isles, and remarkably plentiful in Fermain bay, Guern- 

 sey. This last variety frequents a lower part of the 

 littoral zone than the typical form ; the young are 

 distinctly umbilicate, and resemble in shape and sculp- 

 ture those of T. cinerarius. It is the variety lata of 

 the Bev. B. T. Lowe. The fossil localities for the 

 present species are questionable. Mr. J. Smith enu- 

 merates Ireland, and Mr. Maw Strethill ; but possibly 

 the latter geologist was deceived by the " navvies " who 

 brought him specimens. The case of the Macclesfield 

 deposit has served as a useful warning not to place too 

 much reliance on the discoveries of those ingenious 

 workmen. T. umbilicatus inhabits the north and north- 

 west of France ; Vigo, and Faro in Algarve, on Zoster a 

 (M 'Andrew) ; Gulf of Lyons (Martin) ; Toulon (Gay) ; 

 south coast of the Crimea, in the Black Sea (Midden- 

 dorff). I found the variety Iceta at Bochelle, Mr. 

 M 'Andrew at Corunna, and the Bev. B. T. Lowe at 

 Mogador. 



This littoral species lives in company with T. cinera- 

 rius, but alwavs retains its distinctive character : their 

 mode of locomotion is the same. If either is taken 

 from the shore, and immersed in sea-water, it will expel 

 bubbles of air through the right-hand lappet or fold of 



