PULMONATA. 181 



" In its natural condition the shell is perfectly concealed by the 

 cuirass, in which state the animal has exactly the aspect of a 

 Limax with a very tumid, uneven, large raised cuirass, and thus 

 it is always found in its places of retreat under stones, when moist 

 and in a healthy condition. Removed from its natural abode, 

 or after exposine to a free circulation of air, there soon appear, 

 first a sinus, then a deep wide slit up the posterior half of what 

 appeared before to constitute a uniform tumid cuirass. Through 

 this opening appears the shell, the back part of whose last volu- 

 tion, as the animal becomes more and more dry, is gradually 

 more exposed by the enlargement of the sinus which dilates more 

 paiticidarly on the left side, till finally the whole shell is exposed, 

 with the exception of about a line's breadth of the outer lip, 

 covered by a narrow portion of the ciurass like a border, which 

 becoming broader towards the right side, extends backwards 

 and partly over the sjiire in a kind of broad lateral lobe. The 

 animal is even sometimes completely retracted within the shell, 

 like a Helix ; and had I not observed in the same in(h\'iduals the 

 whole process of transition, from the asjiect of a Limax without 

 the slightest appearance of external shell, to that of a Helix com- 

 pletely contained within one, the identity of the individuals in 

 the two states would have seemed most questionable. 



" The posterior extremity is acuminated, pointed, triangular 

 when the animal is at rest, elongated when in motion, convex 

 and carinated down the middle. The keel is formed by tht- op- 

 position of the two lips of skin which form the edges of the bed 

 in which the jjosterior part of the shell is sunk, and which thus, 

 while giving the appearance of a keel, form in reality a close 

 channel or groove. This is continued a part of the way down, 

 but not to the extremity. The oblique grooves before mentioned 

 on these lips of skin are continued on each side to the extremity 

 of the tail, dividing it into compartments on each side. There 

 is no appearance of a terminal mucous pore. 



" The head, neck, and tentacula of the animal are granulated ; 

 with two very distinct grooves close together do^ii the middle 

 of the neck, beginning between the upper pair of tentacula and 

 an intermediate raised black granulated hne. The cuirass is 

 sti'ongly wrinkled concentrically, hke the lines at the ends of the 

 fingers. The sides of the posterior extremity are, as before de- 

 scribed, divided into regular compartments by equidistant lines 

 running obliquely from the closed groove or keel down its centre 

 to the edge. 



"The general ground-colour of the animal is either cinereous or 

 a very pale reddish brown ; the tentacula and fore ])art of the 

 head and neck rendered dusky by the dark granulations. The 

 cuirass is more or less mottled by large confluent, often distinct. 



