1016 General Notes. 
Paracyclas validalinea, n. sp.—Shell rather large, oblong, sub- 
circular in marginal outline; length and breadth usually unequal; 
dorsolateral portion of the shell strongly produced. Valves ventri- 
cose ; most strongly so at or slightly above the centre ; cardinal line 
strongly arcuate; beaks prominent and strongly curving forward, 
distant, situated centrally or very nearly so. Muscle impressions 
large, and in well preserved specimens distinctly marked; the 
posterior one sub-circular ; the anterior one obliquely subreniform, 
and considerably smaller than the posterior one. Pallial line 
prominent, parallel to which is a prominent row of pustules 
arranged side by side. Surface unknown. ; 
This shell differs from any form previously described that 1s 
known to me. This form is known only by its cast, of which over 
one hundred specimens have been secured. 
Position and locality: Rockford Shales, Rockford, Hackberry, 
and Owens’ Grove, Lowa i : 
Platystoma mirus, n. sp.—Shell very minute; suborbicular m 
outline; spire nearly ona plane with the y whorl; volutions 
about three. Outer volution large, strongly convex, rounded; 
suture not very distinct; aperture sub-circular ; outer lip of mode- 
rate thickness with entire margin; columella lip not distinctly 
produced ; umbilicus closed. Surface smooth. 
Dimensions: diameter, 1 mm. ; height, ê mm. 
Position and locality: lower portion of Rockford Shales, Hack- 
rry, Lowa. : 
Platystoma pervetus, n. sp.—Shell semi-circular to subovate 1m 
outline; spire eleyated but little above the body whorl; volutions 
about three; the body volution very large, rounded, and very 
convex ; suture well defined ; aperture sub-circular ; umbilicus deep. 
Surface smooth. . 
Dimensions: greatest diameter, ? mm. to 1 mm. ; vertical height, 
# mm. to 4 mm. 
Position and locality : lower part of Rockford Shales, Hackberry, 
owa. 
Naticopsis rarus, n. sp.—Shell somewhat subovate in general 
outline; spire slightly prominent, depressed; volutions three; 
convex, rounded ; increasing rather rapidly in size from the ape; 
body whorl large, forming by far the greater bulk of the entire 
shell; broadly rounded on the sides. Suture distinct ; aperture 
subovate ; outer lip thick ; inner lip not defined. Surface smooth. 
Dimensions: height, 1} mm. ; greatest breadth, 14 mm. 
; Position and locality: base of Rockford Shales, Hackberry, _ 
owa. 
Turbo strigillata, n. sp.—Shell turbiniform, thick; spire de- 
pressed, conical; whorls four, increasing ra idly in size from ~~ 
apex; those of the spire convex, but not distinctly rounded ; 
