98 PROCEEDINGS OP THE CALIFORNIA 



I 2. Coluraellar lip little twisted, flattened anteriorly, not apptessed, leaving 

 an umbilical sinus behind it. 

 f ft Diameter about two-thirds of length, or more. Smooth. 



ttXt Outline obovate, often shouldered, whorls scarcely oblique. 



22 ampuUacea GUI. Wh. 6, mouth .80 of length, horn-color; diam. 

 0.42-*0.55, alt. 0.72-*1.00. 



Q. Yar. Lordi Bdird. More shouldered ; diam. *0.50-*0.75, alt. *0.75- 



*1.00. 

  Yar. propinqua Tryon. Wh. 5, mouth .75 of length, spire shorter ; 

 diam. *0.4S-0.50, alt. 0.72-*0.78. 

 Q. Var. coniformis Tryon. Wh. o, mouth .75 of length ; diam. *0.36, 



alt. *0.60. 



23 humerosa GUI Wh. 5, thick, mouth .65 of length, strongly shoul- 

 dered ; diam. *0.38-0.45, alt. *0.50-0.70. 



Var. virgata Gld. Wh. 4-5, mouth .75 of length, less shouldered, 

 striped; diam. *0.2.5-0.40, alt. *0.40-0.65. 

 If ft With strong longitudinal ribs. 



24 costata Newc. Wh. 4, mouth .75 of length, shouldered, ribs 10-14; 

 diam. 0.20-0.30, alt. 0.35-0.50. 



Subgenus APLEXUS Flem. Shell elliptic-oval, sinistral, lustrous, 

 columella slightly indented. 



25 h y p n r u m Linn. Wh. 6-7, mouth .55, diam. ab8ut .40 of length ; 

 diam. 0.20-0.30, alt. 0.50-0.85. 



Subfam. Pompliolinm Dall. Shell depressed, few-whorled, the 

 last nearly including the flattened spire ; base convex, mouth 

 ^usl, imperforate. 

 Genus POMPHOLYX Lea. The only one known. 



26 e f f u sa Lea. Wh. 2)^-3, surface smooth, or with strong growth lines ; 

 diam. *0.32-0.38, alt. *0.25-0.30. 



Subfam. Planorbinm. Shell dextral, spire depressed, usually 

 sunken, whorls visible from below. 

 Genus CARINIFEX W. G. Binn. Shell angled, spire terraced, 

 body-whorl narrowed below, mouth subtriangular, umbilicus funnel- 

 shaped. (Animal still unknown.) ^ 



27 Newberry i Lea. Wh. 5, with 2 principal and 2 or 3 minor angles 

 (the outer ones sometimes replaced by malleations), suture channeled; diam. 

 *0.55 to 0.70, alt. *0.42 to 0.60. 



Yar.? minor Cp. Wh. 3, with but two angles, suture not channeled ; 

 diam. 0.30--0.40, alt. 0.15-0.20. 



Genus PLANORBIS Guett. Spire sunken, outer 2-3 whorls nearly 

 on a plane above, rounded, about as deep as umbilicus, mouth 

 nearly semi-circular, a. 



a. For convenience of comparison. I consider tlie rioM side tlie top, as did aU the older authors, 

 tJius bringing tlic mouth in the dextral pos^ition. 



