58 LIMN^IDJE. 



well as in the lake itself ; but my friend Dr. Laver, of 

 Colchester, who has visited the spot, informs me that 

 " there is no stream running into the tarn, and the 

 small overflow is lost in the boggy soil, and gradually 

 drains over the face of the precipice." 



3. L. per'egra,* MiJLLER. Pl. v. 



Body grey or very pale brown with a greenish tinge, in- 

 distinctly but closely spotted with black, and powdered less 

 thickly with larger specks of a yellowish-grey colour; tentacles 

 flattish, widely diverging, triangular, very broad at the base, and 

 tapering to a point in front, placed at nearly a right angle with 

 the sides of the animal, spotted with greyish-yellow ; eyes rather 

 large, nearly round, black ; foot pale greenish-brown, somewhat 

 truncated in front, rounded behind. 



Shell obliquely ovate, thin, fragile, rather glossy, somewhat 

 transparent, yellowish horn-colour, with irregular striae in the 

 line of growth, and faintly striate spirally, as well as sometimes 

 ridged in the same direction ; epidennis thin ; whorls 5, convex, 

 body whorl tumid, occupying about three-quarters of the length 

 of the shell ; spire produced, apex sharply pointed ; mouth oval, 

 large, very slightly contracted above ; outer lip thin, somewhat 

 reflected ; inner lip broadly reflected and thickened on the pillar, 

 and forming a very small umbilical chink ; fold large, curved. 



Inhabits sluggish streams, ponds, and ditches in 

 every part of Great Britain. It is an exceedingly 

 abundant species ; the size, form, and colour of the 

 shell are very variable, being materially affected by 

 the properties, temperature, and situation of the water 

 it inhabits. It is tolerably active, often leaving the 

 water to climb upon the stems and leaves of sur- 

 rounding plants, and it frequently wanders away to a 



* Wanderer. 



