138 HELICID&. 



tions ; periphery rounded ; epidermis thin ; whorls 6 ; spire very 

 slightly produced, apex obtuse, brownish ; suture deep ; mouth 

 forming three-fourths of a circle, somewhat oblique, sometimes 

 furnished with a slight internal rib ; outer lip thickish, slightly 

 reflected ; umbilicus very wide and deep. 



Inhabits heaths and downs, especially when the 

 soil is dry or sandy, in many parts of Great Britain, 

 but it is rather local. It is a slothful, timid, and irri- 

 table creature, and retreats within its shell the instant 

 it is touched. It feeds upon various plants, and seems 

 to be very partial to thistles. 



Var. i. alba, Charpentier. Shell milk-white, not uncommon 

 with the type. 



Var. 2. minor. Shell smaller. Kendal (J. G. J.), B.C. 



Var. 3. instabilis. Shell smaller, of a darker colour and 

 sometimes streaked or spotted ; spire more raised, umbilicus 

 narrower. H. instabilis, Ziegler. lona (Lowe), Mull (Bedford), 

 Connemara (J. G. J.), B.C. 



Monst. siuistrorsa. Spire reversed. Bridlington (Strickland), 

 B.C. 



IQ. H. ROTUNDA'TA,* MtJLLER. PL. VIII. 



Body slender, slaty-grey, sides paler, finely spotted with black, 

 tubercles large but not prominent, roundish, flattened ; tentacles 

 dark slaty-grey spotted with black, upper pair rather close 

 together at the base, bulbs short, rounded at the tips : lower 

 tentacles diverging, very short and thick and more transparent 

 than the upper ones ; foot rather slender, rounded in front, nar- 

 rowing behind and ending in an obtusely pointed tail. 



Shell compressed, especially below, somewhat thin, scarcely 

 semitransparent, slightly glossy, yellowish horn-colour, with 

 broadish, regularly placed, transverse markings of a reddish- 

 brown colour, and with close-set curved ridges in the line of 

 growth, except on the first whorl which is nearly smooth ; peri- 

 phery obtusely keeled ; epidermis moderately thick ; whorls. 



* Rounded. 



