182 PULMONATA. 



black or dark brown spots or patches. The posterior extremity 

 is of a uniform dusky brown, sometimes olivaceous. Tlie sides 

 are pale cinereous browm. The cuirass and posterior extremity 

 are sometimes also sprinkled with minute, opake, milky dots. 



" The animal is very slightly viscous ; the mucus is hyaline. 

 Length of the largest specimen seen, H inch; of this the tail 

 was i an inch. It is found of all sizes, from this to \ of an inch 

 in length; the usual size is that of the specimen figured. When 

 the animal is at rest, the cuirass occupies two-thirds of the whole 

 length ; when it is crawling, about three-fifths of it ; the neck 

 and tail then extending each about one-fifth beyond it. 



" When in motion it crawls with great activity. Contrary to 

 any other of its tribe that I am acquainted with, if disturbed or 

 UTitated, it only crawls the faster ; and if at rest and contracted, 

 it directly puts itself in motion on being touched or disturbed." 

 — Lowe. 



2. VITRINA. 



Mantle produced and covering the front edge of the last whorl 

 and a part of the spire of the shell. Shell depressed, thin. 

 Whorls two or three, rapidly enlarging, last dilated. Mouth 

 very large. Peristome thin. Columellar edge thin, arched. 



Vitrina, Drap. Tabl. 33. 98, 1801 ; Hist. 23. 30. 119, 1803. 



Lamk. Phil. Zool. 1809 ; Hist. A. s. V. vi. 52. 



Fleminff, B. A. 255. 267, 1828. 



Alters, Heliceen. 

 Semihmax, Ferussac, Essai d'une Method. 1802. 

 Helicohmax, Ferussac, Essai, 1807 ; Prod. 21, 1819 ; Hist. Moll. 

 31, 1821. 



Rang, Man. 157, 1829. 

 Helicolimax A, Blainv. Man. Malac. 462, 

 Cobresia, Hiibner, Monog. v. Test. 1810. 



Studer, Coxe's Trav. Switz. 1789. 

 Vitrinus, Monff. Conch. Syst. ii. 238, 1810. 

 Hyalina, Studer, Syst. Verz. 11, 1820. 



Limacina, Hartmann, N. Alpina, i. 206, 1821 ; in Sturm, Fauna, 

 vi. 41. 



The animal of Vitrina is intermediate in form between a slug 

 (Limax) and a snail {Helix), having the shield-like mantle of the 

 one and the globular external shell of the other. It can draw 

 itself into the shell so as entu'ely to hide itself like the Snails. 



