LYMN-zEIDyE OF NORTH AMERICA. 391 



the individuals resemble solida in being roundish and having tumid 

 whorls, but the resemblance is superficial, the shells having on the aver- 

 age, all the characteristics of catascopium. Several of these specimens 

 are figured on plate XL (figures 23-26). Specimens of catascopium 

 from Lake Champlain, near Burlington, Vermont, are very thin, with 

 rather large shell, and somewhat resemble Lymncea limosa Linne of 

 Europe. Currier's intertexta is a synonyn of catascopium, the Black 

 Lake specimens being almost identical (though thinner) with in- 

 dividuals from Philadelphia (see plate XL, figures 32-35). Currier's 

 types (a cotype figured on plate XL) are scalariform in character, 

 but are otherwise the same as typical catascopium. 



Limncea linsleyi De Kay appears to be an immature form of 

 catascopium. It has no relation to humilis, as may readily be seen 

 by carefully reading the original description. DeKay especially com- 

 pares it with pinguis. Catascopium includes in the synonomy six 

 names, mostly founded on its various mutations : cornea, Val., seri- 

 cata Ziegler, linsleyi DeKay, pinguis Say, intertexta Currier and 

 brownii Tryon. With all of its variations, however, it cannot be mis- 

 taken for any other species when its characteristics are once under- 

 stood. 



Galba catascopium niagarensis Baker. Plate XLII, figures 1-4. 



Lymnea fusiformis Lea, Proc. Amer. Phil. Soc, II, p. 33, 1841; Trans. 

 Amer. Phil. Soc, IX, p. 10, 1844; Obs., IV, p. 10, 1848 (not Lymncea fusiformis 

 Sowb., Mineral Conchology, II, p. 155, pi. 169, 1818, an Oligocene fossil of the 

 Isle of Wight). 



Lymncea fusiformis Wheatley, Cat. Sh. U. S., p. 23, 1843. — Scudder, Bull. 

 Nat. Mus., 23, pp. 33, 44, 201, 1885. 



Limnea fusiformis Hald., cover p. 4, No. 6, 1843. 



Limncea fusiformis Binney, Check List, p. 12, 1860 ; Land & F.-W. Sh. 

 N. A., II, p. 50, fig. 72, 1865.— Tryon, Amer. Journ. Conch., Ill, p. 196, 1867. 



Shell : Thick, solid, fusiform ; periostracum yellowish horn ; 

 sculpture as in catascopium; whorls five to six, flat-sided, broad, rapidly 

 increasing in diameter ; spire short, broadly acute, the whorls flat-sided 

 or only very slightly rounded; sutures slightly impressed; outer lip 

 with internal varical thickening; aperture elliptical, narrow in some 

 specimens, about as long as the spire; inner lip rather broad, tightly 

 appressed to the columella, completely closing the umbilical region ; 

 parietal callus very heavy; columella with a distinct but not sharp 

 fold, axis twisted. 



