66 SKENEID^. 



7 or 8 obliquely striated turns, the last of which is propor- 

 tionally much the largest ; the under side has a small boss or 

 nipple-shaped point in the centre. L. 0-03. B. 0-06. 



Var. 1. trochiformis. Spire more prominent, and umbilicus 

 consequently contracted. 



Yar. 2. maculata. Yellowish-white ; the last whorl spirally 

 ornamented by a double row of circular reddish-brown spots, 

 one above and the other below the periphery. 



Yar. 3. liyalina. Clear- white and transparent. 



Habitat : Plentiful under stones and on seaweeds 

 between tide-marks all round the coast. Var. 1. Shet- 

 land^ Skye, and Lough Larne ; this seems to bear the 

 same relation to the common form as the Helix rupes- 

 tris of Studer and Draparnaud does to the H. umbilicata 

 of Montagu. Var. 2. Channel Isles. A^ar. 3. Skye and 

 Channel Isles. Fossil : Clyde beds (Smith and Cross- 

 key); Fort William (J. G. J.); post-glacial and glacial 

 beds in Norway^ 130-380 feet (Sars). Recent : Spitz- 

 bergen (Torell) ; Iceland (Steenstrup and Torell) ; Scan- 

 dinavia (Loven and others) ; north of France (Mace, 

 Cailliaud and J. G. J.) ; Cannes (Mace) ; Nice (Ve- 

 rany); Spezzia (J. G. J.); Madeira (Johnson, ^c?e Han- 

 ley) ; Greenland (Fabricius and ]M oiler) ; Massachusetts 

 (Gould, as S. serpuloides) ; from Cape Cod northwards 

 (Stimpson) . Although it is a sublittoral species, Malm 

 has dredged it in 10 f. on the Swedish coast, and M^An- 

 di'ew in 15-40 f. on that of Upper Norway. 



This little moUusk feeds upon Lichina pygmcea and 

 small Confervce. It swims with facility in an inverted 

 posture, and occasionally suspends itself in the water by 

 spinning a viscous thread with its foot. When crawl- 

 ing, the shell is carried sideways, not erect. Mediter- 

 ranean specimens are frequently spotted, like our 2nd 

 variety. 



It is the Helix dejwessa of Montagu. 



