MALACOZOA. GASTEROPODA. PULMOBRANCHIATA. 109 



cially small brooks, that of Limnaeus limosus. When not ex- 

 posed to the effects of drought, it is plump and glossy ; but 

 when the reverse it becomes 'wrinkled, and has the shell flat- 

 tened or marked with longitudinal ridges, or irregular sink- 

 ings, like the skull of a New Hollander. It never leaves the 

 water, in so far as I have observed, although the water in 

 summer often leaves it. Yet Muller says, " Buccinum hoc, 

 uti Helix succinea, vere amphibium est ; tempore enim bru- 

 mali, truncis et ramis Tiliarum ultra centum passus ab omni 

 aqua remotarum plurima mhaerentia reperi : " — quod vere mi- 

 nun est. 



2. Limnceus palustris. Marsh Mud-Shell. 



Shell oblong, conical, pointed, thin, horny, semitransparent, 

 of about six turns, which are little convex, distinctly separated 

 by the moderately impressed suture, along which they form an 

 acute but thickened margin, transversely striolate, the last 

 turn large, with faint longitudinal angular ridges ; the mouth 

 ovato-oblong, nearly half the length of the shell, with the 

 pillar-lip expanded so as partially or entirely to cover the um- 

 bilicus ; the colour varying from greyish-yellow to umber or 

 dusky reddish-brown, that of the interior from horn-colour to 

 dusky purplish-brown, of the inner lip from white to purple. 

 Length half an inch, breadth two and a-half twelfths. 



This species might be divided into as many varieties as the 

 last, for, being subjected to the same influences, it undergoes 

 similar modifications. I have not met with it alive of a size 

 approaching to that of specimens from England, its greatest 

 length with us being seven-twelfths, the size and form being 

 about those of Draparnaud's Fig. 2. PI. 3. Not unfrequently 

 the spire is trunculate from erosion or decay of the first turns. 

 A dead specimen, however, found at Don-Mouth in Septem- 

 ber, 1842, although having the spire broken, measured seven 

 and a-half-twelfths in length, and three and three-fourths in 

 breadth. 



The animal elongated, spiral ; with the foot oblong, de- 

 pressed, obtuse behind, dusky green ; the head, tentacula, and 

 neck greenish-black ; the neck transversely rugose ; the collar 

 with the margin thickened, dusky green ; the mantle black, 

 variegated with pale green ; the rest of the body black. 



In pools, lakes, marshy places, and streams, in the maritime 

 and lower inland tracts. 



Buccinum palustre. Muller, Verm. Terr, et Aquat. ii. 131.' — 

 Helix palustris. Mont. Test. Brit. 370. PI. 16. f. 10.— Helix 



K 



