THE NATURAL HISTORY SURVEY. 215 



bicuspid lateral teeth, all longer than wide. "Genital system 

 lacking all accessory appendages." (Pilsbry.) 



Distribution: "Holarctic realm." (Pilsbry.) 

 83. Punctum pygmaeum Drap., pi. xxviii, fig. 20. 



Helix pygmteum DRAP., Tab. Moll., p. 114, pi. viii, figs. 8-10, 1801. 

 Helix minutissima LEA, Trans. Amer. Phil. Soc., Vol. IX, p. 17; Proc., 

 Vol.11, p. 82, 1841. 



Shell: Subglobose, rather strong, umbilicated; surface 

 dull or shining, marked by numerous strong, rounded, ele- 

 vated striae and very fine spiral lines, which are stronger on the 

 base than elsewhere; color reddish or brownish; periphery 

 rounded; sutures very deeply impressed, especially between 

 the last two whorls; whorls four, convex, regularly and gradu- 

 ally increasing in size; spire elevated, convex; aperture some- 

 what oblique, crescentic, ample; peristome simple, rather solid ; 

 columella subreflected, the terminations of the aperture widely 

 separated; umbilicus wide, deep, showing all the volutions to 

 the apex. 



Greater diameter, 1.00; height, 0.50 mill. (11457.) 



Animal: Not observed. 

 Genitalia: Not observed. 



Jaw: ''Arcuate or horse-shoe shaped, composed of thir- 

 teen to nineteen separate rhomboidal plates, more or less 



Fig. 52. 

 Jaw of PUNCTUM PYGM^UM Drap. (After Binney.) 



overlapping, the outer imbricating over the inner plates; the 

 median two or three plates slightly separated, not overlap- 

 ping." (Pilsbry.)* (Fig. 52.) 



Radulaiormu\di: Y+H~ ( r 3 T [ 3); central tooth with 

 a long and narrow base of attachment, the lower outer corners 

 somewhat expanded, but the lower edge straight or only 

 slightly concave; reflection tricuspid, the central cusp short, 

 wide, rather sharp, reaching about a third of the distance from 

 upper to lower edge of basal plate, side cusps very short and 

 wide, rounded; lateral teeth with a base of attachment almost 

 as wide as long, squarely truncated at the lower edge; reflec- 



*Guide to Study of Helices, p. 7. 



