OF NORTHUMBERLAND AND DURHAM. 123 
of the head and before the eyes, sufficiently distinguish it from 
the other genera of the family. The animal is white and retrac- 
tile within the shell, from which it is seldom much protruded, 
keeping its eyes under the protection of the transparent shell, 
through which it looks as through a window. ‘This practice we 
have noticed in several of the Mollusca, whose shells are trans- 
parent. It has no gizzard nor operculum. 
Faminy. Actmonipa, D’Orbigny. 
21. ACT ALON, Montfort. 
1. A. TorNaTILis, Linn. 
Voluta tornatilis, Mont. Test. Brit. 231. 
From deepish water, rather rare. Occasionally found in the 
stomachs of fish. 
The animal of this genus comes very near to that of Bulla, 
having a broad lobed dise in front, without tentacles. We find, 
too, that the branchial aperture is lateral, the cloak being 
closed across the front, and open only on the right side, which 
further confirms us in assigning it a place in this order. The 
operculum can scarcely be considered of more than generic im- 
portance. 
Orpver. PULMONATA, Cuvier. 
Famity. Limactpa, Fleming. 
22. ARION, Feérussac. 
1. A. ater, Linn. (Common black Slug). 
Arion ater, Gray Turt. Man. 104. 
In woods, fields, and hedges, very common. 
Férussac considers the black head and tentacles, and the trans- 
verse black lines round the margin of the foot, to be the only 
permanent distinctive characters in this very variable species. 
The varieties we have observed in this neighbourhood are the 
following :— 
1. Entirely black. 
2. Black, with the sides of the foot yellow or orange. 
