558 



posteriorly twisted, inner lip ending anteriorly in a fold, tooth, 

 or truncature. 



Naucum, Schum. Alicula, Ehrenb. Roxania, Leach. 



Genus 11. Cylichna, Loven. (Shells, Bulla, sp. 101-119. 

 pi. cxxv. f. 132-151.) 



Animal breve, latum. Caput depressum, subquadratum, antice 

 truncatum; vibracula lata, deplanata, libera, recumbentia, trans- 

 versa ; oculi sub eorum basi immersi. Solea brevissima, ovato- 

 quadrata. Pallium limbo incrassato, aperturam postice claudente. 



Testa cylindrica ; spira nulla, vertice umbilicato ; columella 

 callosa, uniplicata. 



Animal short, broad. Head depressed, subquadrate, anteriorly 

 truncate ; tentacles wide, flattened, free, recumbent, transverse ; 

 eyes immersed in their base. Foot very short, ovately quadrate. 

 Mantle with the margin thickened posteriorly, closing the aperture. 



Shell cylindrical; spire none; apex umbilicated; columella 

 callous, with a single plait. 



Bullina, Risso (not Ferussac). Cylindrella, Swainson. Vol- 

 varia, Brown. 



Genus 12. Volvula, Adams. (Shells, sp. 120-124. pi. cxxv. 

 f. 152-156.) 



Animal ignotum. 



Testa subcylindrica, utrinque rostrata ; spira occulta ; apertura 

 angusta; labium obsolete uniplicatum. 



Animal unknown. 



Shell subcylindrical, beaked at both ends; spire concealed; 

 aperture narrow ; inner lip with a single obsolete fold. 



This genus differs from Volvaria in the spire being entirely 

 concealed, and having but a single fold on the fore part of the 

 inner lip ; and from Ovulum and Hyalina in the outer lip not 

 being thickened or reflected externally. 



Genus 13. Lintema, Adarns. (Animal, pi. cxix. f. 9. Shells, 

 Bulla, sp. 125-128. pi. cxxi. f. 52-55.) 



Caput quadrilateral e, auriculis posterioribus nuUis ; oculi in 

 media superticie superiore capitis. Pallium inclusum, postice in 

 limbo crasso productum. Pes lateribus liberis in alis duabus ex- 

 pansis, postice conjunctis, testam circumflexis. 



Testa ovata, depressa; apertura superne siibcanahculata ; la- 

 bium internum appendiculo calyciformi, intus spirah. 



