LIMNEANA. MOLLUSCA. ANCYLUS. 223 



LiMNiE'A CATASCOPIUM. 



Shell ovate, strong, chestnut-broicn ; whorls four, wrinkled, con- 

 vex, the last large ; suture deep ; aperture sub-oval, half tlce length 

 of the shell. 



State Coll., No. 69. Soc. Cab., No. 1304. 



Lymnea catascopiuni, Say ; JVicholsons Encyc. (Jlmer. ed.), pi. 2, f. 3. 

 Limncus catascwpium, Sav ; Amcr. Conch., pi. TjS, f. 2. 



Lymneus cornea, Valenc. ; in Humb. et Bonpl. Recueil d'Ohs. .^c, (teste Fe- 

 russac). 



Shell rather large, oblong-ovate, ventricose, thick and strong ; 

 epidermis chestnut or brownish horn-color ; whorls four or a little 

 more, forming a short, pointed spire, delicately but rather regularly 

 wrinkled by the lines of growth, and these are rendered somewhat 

 corrugated by obsolete revolving lines ; last whorl constituting 

 nearly the whole shell, very much distended ; suture deeply im- 

 pressed ; spire very short, acute at apex ; aperture rather more 

 than half the length of the shell, sub-oval, very little narrowed be- 

 hind ; not dilated ; right lip simple, thick and regularly curved ; 

 left lip having a thick, narrow layer of enamel, and a rather slight 

 fold midway ; umbilicus not open. Length -^-^ inch, breadth -^^ 

 inch, divergence 60°. 



Found in the southern parts of this State, but I have not met 

 with it near Boston. 



Its great solidity, and its remarkably broad, corpulent aspect, ap- 

 proximating in character to Paludi'na, cause it to be easily recog- 

 nised. Its analogue on the European continent is L. pereger, which, 

 however, differs from this in being a less solid shell, in having the 

 aperture somewhat expanded, its anterior "curve broader, and the fold 

 of the pillar less deep. It comes nearer to L. emargindta than to any 

 other American species. 



Genus ANCYLUS, Muller. 



Shell boat-shaped, without a spire, apex pointed, inclining for- 

 wards and to one side ; aperture ovate. 



