244 



NEW YORK STATE MUSEUM 



Fig. 171 Lim- 

 naea columella 



This genus is well represented aniong the recent shells in this 

 vicinity. They may be found in all the streams tributary to the 

 Niagara. 



Limnaea columella Say 1817 (Fig. 171). L. columella 

 Say (1817. Acad. nat. sci. Phil. Jour. 1:14) 



This is a very thin, fragile shell having four whorls, 

 rapidly diminishing, separated By a distinct but not 

 deeply impressed suture; aperture large, more than one 

 half the length of the shell; lip simple, and surface 

 longitudinally wrinkled by growth lines. 



Locality. Goat island gravel pits. 

 Only one specimen of this species was found, leading me to be- 

 lieve that it was an uncommon shell in early post-Pliocene times, as 

 it is at the present time. Lime lake being the only locality 

 in this vicinity where the recent shell occurs. 



Limnaea desidiosa Say 1821 (Fig. 172). L. de- 



s i d i o s a Say (1821. Acad. nat. sci. Phil. Jour. 2:169) 



Shell oblong and subconic, with five very convex 



whorls; suture deeply impressed; last whorl slightly 



swollen; slight growth lines visible with a lens. 



Localities. Goat island. Whirlpool and Foster's fiats. 

 This is the most common Limnaea found in these deposits. 

 Limnaea catascopium Say 1817 (Fig. 173). L. catascop- 

 i u m Say (1817-19. Nich. enc. Am. cd. p. 11, fig. 3. 1834. 

 ^Am. conch, v 6. pi. v, fig. 2; 1841. Haldeman. Monograph 

 6, pi. I) 



Shell thin, sculptured spirally by delicate fines, giving it 



naiaite-'a vcry beautiful appearance under the lens; growth lines 



scopmm j^g^yy ^^ ^j-jg suture, making slight plications; whorls four 



or five, decreasing to an acute apex; aperture about three quarters 



the length of the shell; lip simple, folding back on the columellar 



side and leaving a narrow umbilicus. 



Localities. Goat island. Whirlpool and Foster's flats. 



Genus physa Draparnaud 



The animal of Physa is triangular in general shape; tentacles 

 slender and setaceous; mantle covers part of the shell, the margin 

 folding over the body whorl in a fringe. The shell is sinistral, thin, 

 with an acute spire; body whorl large, inflated and the aperture 

 large and ovaU lip simple. 



Fig. 172 Lim- 

 naea desidiosa 

 x3 



