THE NATURAL HISTORY SURVEY. 331 



Animal: With a short, broad foot which is broadly 

 rounded behind; rostrum short; tentacles cylindrical, blunt at 

 their tips; verge short, bifid, with a globular base; jaw present; 

 lingual dentition of A. porata; rhachidian tooth very short and 

 broad, with a tongue-shaped process from the middle of the 

 anterior surface, reaching beyond the base; intermediate tooth 

 with a short, broad body having a strongly projecting infero- 

 interior angle, and a very long peduncle; formula of denticles: 

 rhachidian, T l ; intermediate, five; first lateral eighteen; sec- 

 ond lateral thirty. (Stimpson.)* 



"Ova-capsules semilenticular in form, with a lamniform 

 limb. Each contains but one egg." (Stimpson.)* 



Distribution: North America. 



KEY TO SPECIES OF AMNICOLA. 



A. Shell 5 mill, or over in length, whorls swollen, spire some- 



what elongated cincinnatiensis 



B. Shell 4 mill, or less in length. 



a. Shell swollen, diameter and length about equal limosa 



b. Shell narrow, diameter about half of length. 



1. Spire obtuse, whorls four emarginata 



2. Spire pointed, whorls five lustrica 



134. Amnicola limosa Say, pi. xxx, fig. 35. 



Paludina limosa SAY, Journ. Phil. Acad., Vol. I, p. 125, 1817. 



Amnicola schrokingeri FRAUENFELD, Pric. Zool. Bot. Gesell, Vienna. 



Amnicola ferruginea CALKINS, Valley Naturalist, Vol. II, No. I, p. 6, 



1880. 



Shell: Conic, bulbous, subimperforate, nearly as broad as 

 high; color light or dark brown, without bands of color; sur- 

 face shining (except when covered by deposit of foreign mat- 

 ter, as is frequently the case), lines of growth numerous, fine, 

 wrinkled, crowded; sutures well impressed; whorls four to five, 

 more or less inflated, regularly increasing; spire obtusely conic, 

 swollen; aperture orbicularly ovate, rounded above and below, 

 dark horn-color within; peristome sharp, simple, a little thick- 

 ened on the inside, almost continuous; columella lip covered 

 with a thin callus; base of shell rounded, subumbilicate. 



Length, 5.00; width, 3.25; aperture length, 2.10; width, 1.50 mill. (10498.) 

 5.00; " 4.00; " " 2.60; " 2.10 " 



5.00; " 4.00; " " 2.80; " 2.10 " (13052.) 



Animal: White and transparent, brownish on the head; 

 foot short, rather wide, about two and one-half times as long as 

 broad, auriculated before, rounded behind and constricted in 



*Binney, I. c.,p. 80-81. 



