88 TRACHELIPODA. 



Three-fourths of an inch long. Inhabits the rivers of the Ar- 

 chipelago. 



Genus 65. — MELANIA. — Lamarck. 



Generic Character. — Shell turrited ; aperture entire, ovate or 

 oblong : effuse at the base ; columella smooth, and incurvated ; 

 with a homy operculum. 



Melanin amarula — The Crowned Melania. Plate XIII. 

 fig. 8. Ovate-oblong, thick ; longitudinally wrinkled ; trans- 

 versely striated at the base of the body; upper margin of the 

 volutions crowned with triangular tubercles, from which eman- 

 ate ciliated spines ; colour deep chestnut, covered with a black 

 epidermis. One and a half inch long. Inhabits the rivers of 

 India. 



FAMILY VIII. LYMN.^CEA. 



The animals of this tribe are amphibious, usually without an 

 operculum ; and having flattened tentacula ; shell spiral, generally 

 smooth on the external surface ; the margin of the outer lip is 

 always acute, and not reflected. 



Genus 66.— LY:\IN^A.— Bry^wiere. 



Generic Cliaracier — Shell oblong, som-etimes turrited; spire 

 produced ; aperture entire, oblong ; the outer lip acute ; the 

 lower part of the inner lip rising on the columella, and forming 

 an oblique plait j destitute of an operculum. 



Lymnaa stagnalis. — The Pond Lymn^a. Plate XIII. fig. 

 9. Oblong, body ventricose ; spire very acute and subulate ; 

 aperture large and ovate ; horn-coloured. Two inches long. 

 Inhabits the ditches and ponds of Europe. 



Genus QL—VBY^A.—Drapernaud. 



Generic Character. — Shell generally sinistral, convolute, ova., 

 or oblong ; spire prominent ; aperture longitudinal, contracted 

 above ; columella twisted ; outer lip very thin, acute, partly 



