100 HELICID^E. 



Animal grey, shining ; foot thin ; tentacles long. 



Shell the tenth of an inch in diameter, glossy, 

 dark horn-coloured, with six rounded volutions, 

 which are much raised and strongly defined; the 

 base prominent, with a depression in the centre 

 forming an incipient umbilicus ; aperture transverse, 

 narrow, as high as broad ; with a very thin margin 

 reflected only near the depression, which in young 

 shells is hardly visible. Varies in the intensity of 

 the colour and in transparency, the specimens found 

 in very damp situations being generally much darker 

 and more polished ; epiphragm transparent. 



Mr. Alder observes that the small variety is not 

 uncommon ; it is darker coloured, and with very 

 delicate and beautiful concentric striae on the base 

 only visible with a high magnifier, which induced 

 him at first to consider it distinct ; but on closer ex- 

 amination he found slight traces of these striae visi- 

 ble on the full-grown and decided specimens of H. 

 falva ; he has therefore not ventured to separate it. 

 (1. c. 108.) 



4. HELIX. (Snail.) 



The animal moderate, with an elongate depressed 

 foot, and a large, produced, central, spiral body 

 covered with a subglobose or depressed shell, 

 with a lunate mouth, which is generally broader 

 than long, strengthened with an internal thick- 

 ened rib, and more or less reflexed edges ; ten- 

 tacles four, the two lower small, club-shaped. 

 Tongue broad, with many (100 to 200) longi- 

 tudinal series of flat square teeth, with rounded 

 tips. 



