1910.] NATURAL SCIENCES OF PHILADELPHIA. 669 



brown; with a cream-colored band near the white lip. Spire nearly 

 flat, concave in middle, composed of 2f slightly convex whorls, the 

 last forming a rather raised ring about the sunken apex. The body 

 whorl is rounded with perceptible angulation above the periphery. 

 The base is convex, obtusely angular at the edge of the deep umbilicus 



Fig. 2. — Planorbis uliginosus n. sp. 



and showing a few very indistinct spiral scratches near the lip. Aper- 

 ture oblique, orbicular, with a convex very heavy white callus, covering 

 the inside of the lip and parietal wall. The columella is heavy, rather 

 straight, but not forming much of an angle with the base. The surface 

 is covered with fine irregular growth lines above, but smoother on the 

 base. No spirals seen under a high magnification, except the above- 

 mentioned scratches. Young specimens are more corneous, and 

 resemble P. dilatatus Gld. Sometimes young ones have a very dark 

 brown lip edge. 



Alt. 1.3, diam. 3 mm. 



Locality. — The types are from Pembroke Marsh, near Hamilton, 

 Bermuda; quite plentiful. 



This shell differs from P. dilatatus Gld. by its thick lip, stronger 

 keel, more depressed body whorl, higher spire. It has a larger umbilicus 

 than P. a. avus Pils. not so flat as P. rubellus St., and lacks the very 

 strong keel of P. alabamensis Pils. Types in the collection of the 

 Acad. Nat. Sci. Phila., No. 100,336. 



Planorbis imus n. sp. Fig. 3. 



Shell perspective umbilicate; carinate; lenticular; thin; grayish- 

 yellow; apex depressed; spire convex, truncate, sides descending to 

 the acute periphery. Suture impressed, whorl 2\, moderately convex, 

 surface covered with close incremental striae. Aperture oblique, 

 sagittate, broader than high, peristome thin, superior edge arcuate, 

 nearly vertical above keel, then gradually slopes to angle of outer lip, 

 basal margin evenly arcuate, columella narrow, parietal wall indented 

 by the peripheral keel, covered with a thin callus. 



