360 BULLIDiE. 



concave, umbilicated ; aperture as long as the shell ; inner 

 margin without columella ; outer lip trenchant. 



Teeth, central one, laterals numerous, uniform, in an arched 

 series. Animal partly investing, but not entirely covering the 

 shell. Eyes conspicuous, sessile on the middle of the frontal 

 disk. Mantle with the outer margin forming a thick, fleshy 

 lobe. Foot with the lateral lobes moderate, and the hind-part 

 not extending beyond the shell. The species of this genus 

 inhabit sandy mud-flats, the slimy banks of river-mouths, and 

 brackish places near the sea; at low-water some of them conceal 

 themselves in the mud and under sea-weed, exuding large quan- 

 tities of mucus to maintain the moisture of their skin ; they 

 feed on bivalves and other mollusca, which they swallow whole, 

 reducing and crushing them afterwards by the calcareous plates 

 of their powerful gizzard. The shells of IBulla, as restricted, are 

 rather solid, smooth, and mottled and marbled like birds' eggs. 



Haminea, Leach. 



Example. — H. hydatis, Linn. (Ixxxvii, 31, 38). 



Shell oval-globular, spiral, ventricose, corneous, thin, covered 

 by a slight, smooth epidermis ; spire involute. May be distin- 

 guished from Bulla immediately b\^ the want of color in the shell. 



Atys, Montfort. 



Example. — A. naucum^ Linn. (Ixxxvii, 39). 



Shell rather solid, uncolored, with a smooth epidermis; 

 usually spirally striated ; spire scarcely visible ; aperture longer 

 than the inner margin at both ends ; columella with a single, 

 more or less obsolete plication. 



The animal is blind, or the eyes are subcutaneous. 



LAONA, A. Ad. Semiovate, thin, strife of growth lamellar, 

 spire hidden; aperture with the inner lip arcuated, outer lip 

 simple. A. zonata, A. Ad. Japan. 



DiNiA, H. and A. Adams. Shell ovoid, subtruncated behind, 

 longitudinally striated ; inner lip truncated anteriorly, termi- 

 nating in a tooth-like projection. A. dentifera., Ad. (Ixxxvii, 40). 



SAO, H. and A. Adams. Shell pyriform, ventricose in front ; 

 umbilicated ; apex involute ; aperture narrow behind, wide in 

 front ; columellar lip reflected ; outer lip thin, sinuous. A.pyri- 

 f or mis (Ixxxvii, 41). 



PHYSEMA, H. and A. Adams. Shell small, thin, hyaline, glob- 

 ular; umbilicated; ver}^ finely longitudinally striated ; columella 

 a little arcuated, reflected ; outer lip thin, free behind, developed 

 in the middle. A. hiemalis, Couth. (Ixxxvii, 42). 



ROXANiA, Leach. Shell ovoid, solid, perforate, decussately 

 striate, transversely profoundly sulcate, the sulcations strongly 

 punctate ; aperture narrow, dilated in front : inner lip sharp. 



