MELANTHO. 



291 



[*Thc form known as M. ititcg-ra has not been found in Now 

 England, but for the sake of comparison I give the following de- 

 scriptions and figures : — 



Fig 554. 



Melantho decisa. 



Melantho decisa. Shell imperforate, elongate- 

 ovate, rather thick, smooth, surface hardly broken 

 by lines of growth, with microscopic revolving 

 stria; ; greenish, with irregularly disposed brown 

 streaks marking the edge of former peristomes, 

 uniformly chalky-white under the epidermis ; spire 

 truncated, one or two whorls of it alone remaining, 

 apex entirely removed ; remaining whorls three 

 and a half, convex, the last equalling two thirds 

 of the shell's length, imperforate ; aperture oval, 

 oblique, more than one half the length of the last 

 whirl, bluish-white within ; peristome externally 

 of a darker color, simple, acute, somewhat sinu- 

 ous, iti terminations joined by a thin callus on 

 the parietal wall, entering within the aperture. Length of axis, thirty-seven : greatest 

 breadth of body whorl, seventeen ; length of aperture sixteen ; breadth, eleven mill. 



Operculum arcuated, convex, horny, concentric, nucleus nearer the columellar margin. 



MeJanllio decisa, var. iniegra. Shell imper- Fig 555. 



fofatc, elongate-ovate, quite thick, smooth, 

 surface hardly broken by lines or wrinkles 

 of growth, marked with delicate revolving 

 striae ; greenish, with darker streak-;, mark- 

 ing the edge of former peristomes, uniformly 

 chalky-white under the epidermis ; spire 

 elon:.iated-conic, apex perfect, acute ; whorls 

 five, convex, the last equalling two thirds 

 the shell's length, imperforate ; aperture 

 oval, narrowed above, oblique, more than 

 half the length of the body whorl, milky- 

 white within ; peristome externallv of a 

 darker color, simple, acute, somewhat sinu- 

 ous, its terminations joined by a thin, transparent callus on the parietal wall of the aper- 

 ture, more heavily thickened and white above and below. Length of axis, twenty-four ; 

 greatest breadth of body whorl, fifteen ; length of aperture, fifteen ; breadth, eleven mill. 



Operculum as in M. decisa. 



Female of M. decisa, 

 var. intesra. 



Male of Jlf decisa, 

 var. Integra. 



In general terms it may be said that the fonn 



known as M. integra differs from M. decisa bv being 



more elongated, having a perfect apex, a smaller and 



whiter aperture, and more prominent revolving strise. 



These characters are only comparative. The two 



forms are not distinguished by any decided, constant, 



specific characters. Fig. 55G represents young shells, which are more 



globose, comparatively, than the more mature ones. 



Fig. 553. 



Young of M integra. 



* The remarks in the brackets are bv me. — "W. G. B. 



