MELANTIIO. 



41 



fig. 79. 



Fig. 80. 



MelautliO decisa, Say.— Shell imperforate, elongate-ovate, ratlier 

 thick, smooth, surface hardly bro- 

 ken by lines of growth, with mi- 

 croscopic revolving striae ; green- 

 ish, with irregularly disposed 

 brown streaks marking the edge 

 of former peristomes, uniformly 

 chalky white under the epider- 

 mis ; spire truncated, one or two 

 whirls of it alone remaining, 

 apex entirely removed ; remain- 

 ing whirls 3.}, convex, the last 

 equalling two-thirds of the shell's 

 length, imperforate ; aperture 

 oval, oblique, more than one-half 

 the len-tli of the last wbirl, bluish-white within; 



peristome externally of a darker color, simple, acute, some- 

 what sinuous, its terminations joined by a thin callus on 

 the parietal wall, entering within the aperture. Length 

 of axis 37, greatest breadth of body wbirl 

 17 ; length of aperture 16, breadth 11 mill. 



Operculum arcuated, convex, horny, con- 

 centric, nucleus nearer the columellar mar- 

 gin. 



Melanlho decisa. 



Mtlantho decisa. 



Fig. 82. 



Limnapa decisa, Say, Nich. En. ed. 1, 1817 ; 

 ed. 2, 1818, pi. iii, f. 6. 



Operculum 

 - , , - of Mrlaiitho 



MelarUhodeeisa. Paludina decisa, Say, 1817, Nicholson's .j,,^,,. 



Encycl. pi. iii, f- 6 {Limnsea of earlier 

 editions) ; Amer. Conch. I, pi. x (1830) ; ed. Binney, p. 49, 159, 

 pi. X, fig. 1, pi. \xx, fig. 6; ed. Chenu, 16, pi. ii, f. 5.-Philippi, 

 Conch. Ill, 3, pi. i. f. 8 (1848).— Haldeman, Mon. p. 4, pi. i (1840). 

 -Gould, Invert, of Mass. 227, wood-cut, p. 144 (1841).-Adams, m 

 Thompson's Hist, of Vermont, p. 151, fig. (1842).-DeKay, N. Y. 

 Moll p. 84, pi. vi, f. 131; vii, 134 (1843).-Chenu, III. Conch, i, f. 

 1-5 -Mks. Gray, Fig. Moll An. pi. cccx, f. lO.v -Potiez et Michaud, 

 Gall, des Moll. I, 247, pi. xxv, f. 13, 14.-Kustek in Chemn. ed. 2, 

 p. 13, pi. ii, fig. 14-19.— Reeve, Con. Icon. 45, a, c, d, excl. 45 b (= 

 Pal. ponderoso), Mar. 1863. 

 Melania ocularis, Menke, Syn. Meth. p. 134, teste Kuster. 

 Paludina Wnosa, Valenciek>-es, Rec. d'Obs. II, p. 253, 1833, teste Kustek 



and Haldeman. 

 Paludina ponderosa jun., Deshayes in Lam. VIII, 516 (1838), ed, 3, III, 455. 

 Paludina heterostropha, Kirtland, Ohio Rep. p. 175 (1838).-Tappan, Am. 



Journ. Sc. [i], XXXV, p. 269, pi. iii, p. 2, 1839. 

 Paludina microstoma, Kirtland, Ohio Report, p. 175 (1838). 

 Paludina rufa, Haldeman, Mon. Ill, p. 3 of wrapper, pi. in, f. 1 (1841). 

 15 



