GASTEROPODA. 



105 



hot countries some species are often seen on the trees near 

 the coast, and on the rocks elevated above the surface of 

 the water; they remain stationary on the latter during 

 the hottest hours, even when it is painful to walk on them 

 from their great heat : they leave the water early in the 

 morning, but return at night. These circumstances prove 

 that, although marine, many species are amphibious. They 

 seem to exist between the tide marks. Woodward men- 

 tions that L. rudis places itself in situations where it is 

 scarcely reached by the tide; it is viviparous, and the 

 young have a hard shell before they are hatched. — About 

 9 British species are known ; others are found in various 

 parts of the world. 



Philippi mentions Nina Gray, and Tectus Montf. ; as 

 sub-genera. 



Modulus. Gray. (Monodonta Soic, not Lam.) — Shell 

 orbicular, strongly curved, umbilicated or 

 not ; mouth round or rhombic ; inner lip 

 with an acute tooth, or separated from 

 the outer lip by a deep notch; the oper- 

 culum circular, thin, (with numerous whorls ?) 

 and a central nucleus. Animal, with a very Module tectum. 

 long snout, the tentacula having the eyes 

 half way up, no frontal lobes ; the foot simple, with no 

 side appendages. — Few species; no fossils. 



From the seas of the Torrid Zone. 



Risella. Gray. (Bembicium 

 Phil.) — Shell shaped like a Trochus, 

 with a flat angular or concave base ; 

 the whorls keeled, aperture rather 

 square, compressed ; generally dark 

 coloured or variegated ; operculum 

 partly spiral. Animal, with a snout-formed head, length 



