214 THE CHICAGO ACADEMY OF SCIENCES. 



small, narrow projection; reflection tricuspid, the central cusp 

 very long, rather wide, and reaching to the border of the base 

 of attachment; side cusps short and wide; the fifth tooth is a 

 modified lateral, with a much shortened central cusp; marginal 

 teeth wider than long, reflection with three cusps, the inner 

 cusp being longer than the outer and bifid; the outer cusps are 

 small and narrow; the eleventh and twelfth marginals have 

 three outer cusps instead of two; all the cusps have rounded, 

 well developed cutting points (Fig. 51). There are over 75 

 rows of teeth. 



Distribution: "Ontario and Quebec to Florida, west to Rio 

 Chania and White Oaks, New Mexico (Pilsbry). Manitoba 

 (Hanham). 



Geological distribution : Pleistocene; Loess. 



Habitat: In damp situations, under loose bark, in rotting 

 wood, and under sticks, stones and leaves. Associated with 

 Pyramidula striatella, Zonitoides arboreus, etc. 



Remarks: A small species, at once distinguished by its 

 flat whorls and armed aperture. The teeth within the aperture 

 are placed as follows: one pair near the. aperture; a second 

 pair is placed within the aperture, a third or half a whorl from 

 the opening, and a third pair (when present) still farther within 

 the aperture. Each pair is placed one above the other, the 

 superior tooth being at or a trifle above the periphery, and 

 the inferior between that point and the base of the aperture. 

 When the animal is in motion the shell is carried almost flat, 

 the eye-peduncles' and tentacles pointing upward at an angle 

 of 85 degrees. The anterior part of the animal is much in 

 advance, of the shell, the latter being placed almost on the 

 posterior extremity. This species is fully as abundant as the 

 last, and is almost always found associated with it. It is one 

 of the neatest of the smaller Helices. 



Subfamily Punctlnae. 



"Jaw composed of sixteen to twenty-four separate pieces." 

 (Pilsbry.) 



GENUS PUNCTUM Morse, 1864. 



Shell: Small, discoidal, aperture subcircular, peristome 

 thin. Jaw composed of numerous separate plates, which partly 

 overlap each other. Radula with a unicuspid central tooth and 



