557 



Right part of the mantle fleshy, equaUing in length the foot ; the 

 left part tliin, adhering. Foot short, subquadrate, the sides 

 anteriorly reflected and covering a small part of the fore part of 

 the shell. 



Shell ovately globose, convoluted; columella none; spire sunken 

 and tubular ; aperture the length of the shell, outer margin 

 acute. 



Bullus, Mont. Vesica, Swain. Cyrnh'mm, Adanson. Rhizorus, 

 Montf. 



Genus 9. Haminea, Leach. (Animal, pi. cxix. f. 7. Shells, 

 Btdla, sp. 56-78. pi. cxxiv. f. 81-106.) 



Corpus oblongum. Caput latum, depressum, elongatum, pos- 

 tice bilobatum ; oculi sessiles in medio capitis. Pallium parte 

 externa (vel dextra) valde dilatata, incrassata, truncata, postice 

 ultra testam extensa. Pes brevis, subquadratus, alis duabus, 

 magnis, natantibus, majorem partem conchse obvelantibus. 



Testa convoluta, cornea, tenuis, transversim striata, columella 

 spiraque destituta. 



Body oblong. Head broad, depressed, elongated, posteriorly 

 bilobed ; eyes sessile on the middle of the head. Mantle with 

 the right or external part greatly dilated, thickened, truncated 

 and extending beyond the shell. Foot short, subquadrate, with 

 two large swimming lobes, which nearly cover the shell. 



Shell convolute, thin, horny, transversely grooved, destitute of 

 columella or spire. 



Genus 10. Atys, Montfort. (Animal, pi. cxix. f. 8. Shells, 

 Bulla, sp. 79-100. pi. cxxiv. and cxxv. f. 107-131.) 



Caput subtrigonale, depressum, postice bilobatum; oculi subcu- 

 tanei, in medio capitis. Pallium parte dextra incrassata, truncata, 

 postice ultra testam extensa. Pes brevis, subquadratus, lateribus 

 reflexis, antice dilatatis, supra anteriorem partem conchse dispositis. 



Testa alba, sohda, transverse striata ; labrum postice tortuosum, 

 labium antice plicatum vel subtruncatum. 



Head subtrigonal, depressed, posteriorly bilobed ; eyes sub- 

 cutaneous, in the middle of the head. Mantle with the right 

 margin thickened, truncated, and prolonged posteriorly beyond 

 the shell. Poot with the sides dilated in front, reflexed and 

 folded over the fore part of the shell. 



Shell white, solid, colourless, transversely striated ; outer lip 



4 c 2 



