138 HELICIDjE. 



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

 slightly produced, apex obtuse, brownish ; suture deep ; 7nouth 

 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. sinistrorsa. — 6)^/r^ reversed. Bridlington (Strickland), 

 B.C. 



19. H. ROTUNDA'TA,* MULLER. 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 ; epider?nis moderately thick ; whorls, 



* Rounded. 



