THE NATURAL HISTORY SURVEY. 241 
are similar, narrower, and bi- or tricuspid; the marginals are 
low, wide and serrated. 
Distribution: Universal. 
SuscEeNnus VERTILLA Mog.—Tand. 1855. 
(Angustula Sterki. 1889.) 
This group is ‘mainly characterized by the long and high 
gular lamina.” (Sterki.) | 
96. Vertigo milium Gould, pl. xxx, fig. 16. 
Pupa milium GOULD, Bost. Journ, Nat. Hist., Vol. III, p.402, pl. iii, fig. 
23, 1840. 
Shell: Small, subcylindrical, smooth shining; growth lines 
very fine, a little oblique; nucleus smooth; color dark chest- 
Regt (sty Ne 
Lavatceae chil) 
i) 
~ 
VERTIGO MILIUM Gould. (Original.) 
nut; whorls five, rounded, somewhat regularly increasing, 
decreasing to a bluntly rounded apex; sutures impressed; 
aperture obscurely semicircular, lateral, truncated above; the 
“circumference” of the aperture is “made up of two curves of 
different radius uniting in the peristome, where the junction 
causes an angle projecting inwards, the smaller curve compris- 
ing about one-fourth part and forming the superior portion of 
the peristome;’’? aperture six-dentate as follows: two sharp, 
projecting teeth of about equal size placed on the parietal wall 
and dividing that region into three nearly equal parts; one on 
the columella, large, massive, broad; a third placed on the 
outer lip above or at the junction of the two radii, long, curved, 
ridge-like, pointing directly between the two parietal teeth; a 
fourth on the base of the lip, small, conical, tubercular; and one 
large, entering, elevated, long lamina, which begins on the 
base of the lip and curves backward until it disappears behind 
the columella tooth (this is the ‘gular lamina” of Sterki); per- 
istome white or brownish-white, reflected, the terminations 
separated, but joined by a prominent callus; umbilicus well 
marked, open, deep; base of shell rounded (Fig. 70). 
*Binney, Man. Amer. L.S., p. 332, 
