156 PUPILLA, AMERICAN. 



1. PUPILLA STERKIANA (Pilsbry). PL 19, figs. 16, 17. 



The shell is cylindric with short, rounded summit and ob- 

 tuse apex ; rimate and minutely perforate ; cinnamon-brown. 

 The surface is dull ; the embryonic iy 2 whorls coarsely, irreg- 

 ularly reticulate-granulose, following whorls having narrow, 

 strongly retractive axial riblets, about one-fourth as wide as 

 the intervals. The whorls are strongly convex, suture deep, 

 the last whorl somewhat compressed laterally, without crest 

 or noticeable contraction behind the lip. The aperture is 

 somewhat oblique, squarish. Peristome expanded, thickened 

 and whitish on the face and within, narrow and abruptly 

 bent near the posterior insertion; margins connected by a 

 short, whitish, adnate callus. In oblique view in the aper- 

 ture the columella appears weakly subtruncate below, or in 

 some specimens there is a distinct tooth (fig. 16). 



Length 4.5, diam. 1.6 mm. ; 7% whorls. 



Length 3.8, diam. 1.65 mm. ; 6% whorls. 



Lower California: San Ramon (C. B. Orcutt). 



Pupa sterkiana PILS., Proc. A. N. S. Phila., 1889, p. 411, 

 pi. 2, f. 2, 3. 



This species differs conspicuously from all other known 

 Pupillae by the sculpture of both embryonic and later whorls, 



2. PUPILLA MUSCORUM (L.). PI. 18, figs. 12 to 16. , 

 Description on page 173. American specimens rarely have 



the lip so much thickened or the white or yellowish area be- 

 hind it so extensive as most European shells, though Euro- 

 peans similar to the American in these characters are readily 

 found. 



It differs from P. blandn by the much shorter and smaller 

 teeth, the palatal fold small and tubercular when present. 

 Some of the thinnest muscorum resemble P. hebes rather 

 closely. 



In limestone districts the white crest and the lip-callus are 

 strongly developed, as in pi. 18, figs. 13, 14 (limestone quarry 

 at Thomaston, Me.), and over much of New York State. 

 "Where the rock is granitic or deficient in lime the crest is 

 usually lower, of a reddish brown color but lighter than the 



