290 



PALUDINID^. 



Cocfiira Virginiana, Sf-c. Lister, Conch, t. 127, fig. 27 (1770). 

 Petiver, Gazophyl- t. 116, fig. 18. 



Melantho decisa, W. G. Binnky, L. and Fr. Shells, iii. figs. 79-82 (1862), excl. syn. suh- 

 solida. 



Fig. 552. 



M. rlecisa. 



Fig. 553. 



Opcrruhim 

 of M. de- 

 cisa. 



Shell ovate-elongate, thick and strong, color varying from yellow- 

 ish-green to dark olive-green ; whorls five, regularly convex, inclin- 

 ing rather abru])tly towards the suture, so as to form a 

 moderate shoulder ; surface marked with fine wrinkles 

 of growth, and occasional stripes of dark purplish, in- 

 dicating the position of preceding apertures ; also with 

 minute, revolving lines, which, in young specimens, 

 when viewed in the water, are seen to he garnished 

 with fine, puljescent hairs ; two or three of the whorls 

 at the apex are usually broken off, leaving an irregular, 

 eroded surface ; aperture oval, not exceeding half the 

 length of the entire shell, forming an angle above ; lip simple, very 

 sharp, until, as it rises towards the columella, it becomes 

 thickened, and, turning outwards, forms a smooth, rounded 

 margin, leaving no umbilicus ; a thick enamel spreads 

 across the preceding wliorl, margined with purplish ; in- 

 terior bluish. Operculum thin, ovate, beaked, with a 

 groove from the centre to the tip of the beak. Length, 

 one and one tenth inches ; breadth, seven tenths of an 

 inch ; divergence, fifty-six degrees. 



Animal with a broad, tongue-shaped foot, drawn out into angles 

 each side in front, of a livid olive color varied with dark, vivid, 

 orange, transverse spots above, and minutely dotted with the same 

 beneath ; tcntacula olive above, spotted with orange, lighter below. 

 Eyes on a niche at the exterior base of the tentacula. 



Found in ponds and muddy streams, usually concealed under 

 shelving banks, or imbedded an inch or two among loose mud and 

 roots. 



This is the only large species inhabiting the waters of New Eng- 

 land. It is less massive than M. pondcrosa^ita whorls more convex, 

 and its aperture less elongated. It is less globular when young 

 than Vivipara sub-piirpurea, and the spire in the adult more sym- 

 metrical. The young are excluded in a living state with a shell of 

 three complete whorls. It is peculiar for the almost constant loss 

 of its tip. 



Found in all eastern North America, from the Rio Grande to 

 Nova Scotia and the Canadas. 



