TRACHELIPODA. 101 



Genus 64 MELANOPSIS.— Xa/warcA. 



Generic Character. — Shell turreted ; aperture ovato- 

 oblong, entire ; columella with a callosity above, truncated 

 at the base and incurvated; the outer lip separated from 

 the inner by a sinus ; aperture with a horny operculum. 



Melanopsis is distinguished from Melania, by the columella being 

 callous at the upper part, and the base truncated as in Achatina ; it 

 difiers from Pirena in having only one sinus, or a widened opening at 

 the base of the shell. 



Melanopsis laevigata. — The Polished Melanopsis. 

 Plate XIII. fig. 28. Ovate, conical, smooth, of a chestnut 

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

 of the Archipelago. 



Genus 65.— MELANIA.— Za/rtorc^. 



Generic Character. — Shell turreted ; aperture entire, 

 ovate or oblong, effuse at the base ; columella smooth, and 

 incurvated; a horny operculum. 



Melania amarula. — The Crowned Melania. Plate 

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

 transversely striated at the base of the body ; upper margin 

 of the volutions crowned with triangular tubercles, from 

 which emanate straight slender spines ; colour deep chest- 

 nut, covered with a black epidermis; aperture bluish-white. 

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



family IX. LYMN^ACEA. 



Animals 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. They live in fresh water, 

 but come to the surface to respire. 



Genus 66 — LYMNiEA Bruguiere. 



Generic Character. — Shell oblong, sometimes turreted, 



