LAMELLIBRANCHIATA. 625 
Saffordia.] 
the margin is rounded in S. striatum. The four or five Cincinnati species known to 
me are all much higher posteriorly. 
Formation and locality.—Middle Galena, Goodhue county, Minnesota. The exact locality is about 
thirteen miles south of Cannon Falls. 
Genus SAFFORDIA, n. gen. 
Shell rather small, transversely subovate, moderately convex, equivalve, very 
inequilateral; back arcuate, beaks anterior, not large, curving obliquely inward and 
forward; umbonal ridge moderate; between the ridge and the dorsal edge a more or 
less distinct sulcus. A sharply defined lunule beneath the approximate beaks, while 
posterior to them there extends to the extremity of the hinge’an equally distinct 
escutcheon. Hinge plate thin, arcuate, with one horizontal wedge-shaped cardinal 
tooth in the left valve which entered into a corresponding cavity in the under side 
of the hinge plate of the right valve immediately behind the beak. Posterior half 
of hinge consisting of a slender lateral tooth in the left valve and a corresponding 
furrow in the right. Anterior to the center an elongate depression for the reception 
of an internal ligament. Anterior muscular scar distinct, deep, subcircular, situated 
beneath the lunule; pallial line simple, submarginal, posterior scar undetermined. 
Test rather thick in the anterior part. 
Type: S. ventralis, n. sp. 
Beside the type, the Hudson River strata of Fillmore county, Minnesota, contain 
another species having the characters ascribed to this genus. This I published 
recently as a new species of Cuneamya, giving it the specific name sulcodorsata. It 
is a more elongate shell but otherwise closely related to S. ventralis. A third species, 
this one from the Galena, I described from casts of the interior as Cypricardites ? 
modestus. 
The position of Saffordia seems to be near the Devonian Grammysia, the hinge 
being similar in the two genera, though not by any means identical. In Grammysia 
namely, as is shown in Hall’s work on the Devonian Lamellibranchiata (Pal. New 
York, vol. v, parti, plate tvu, fig. 6), there is no cardinal tooth in the left valve as in 
Saffordia, nor are the slender posterior lateral teeth represented. Another dis- 
tinguishing feature of the latter, and one that is common to many Lower Silurian 
shells, is found in the greater depth of the anterior muscular scar. In the genus 
Cuneamya the hinge, aside from the escutcheon, is quite different, the test is very. 
thin, and the muscular impressions exceedingly faint, while the back, instead of 
being arcuate, is concave behind the beaks, the latter being also tumid and much 
more prominent. 
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