104 The American Geologist. August, i89a 
plate is long, straight, and bears twenty or more small teeth, 
while on the anterior part only nine are to be counted. In the 
vicinity of the beak the teeth, especially those on the posterior 
side, are very small. Anterior muscular impression deep, sit- 
uated immediately beneath the end of the hinge. Its posterior 
side is defined by a strong vertical thickening of the shell. Pos- 
terior scar distinct, but less sharply impressed than the anterior, 
situated at the end of the hinge just within the thin postero- 
cardinal border of the shell. 
Judging from the interior this shell, though more elongate, 
evidently belongs to the section of the genus of which T. ventri- 
cosn Hall, T. angel a Billings, T. coiitr((ct(( Qalier, and T. pJanodor- 
sata Ulrich, are typical members. In all of these the muscular 
scars are deep and large, excavating the shell under the ends of 
the hinge plate so that they are exceptionally prominent in casts 
of the interior. 
Formation and locality: In shaly strata, equivalent to the 
Black River limestone, at a point about eight miles south of Can- 
non Falls, Minnesota. 
EXPLANATION OP PLATE VII. 
Figs. 1 and 2, Cleionychia rhomboidea, n. sp. 
Lateral and anterior views of a right valve. 
Figs. 3 and 4, Cyfricardites oviformis, n. sp. 
Anterior and lateral views of a cast of the interior of a left valve, the 
posterior outline restored. 
Figs. 5-7, CvrRicARDiTES (?) MODESTus, n. sp. 
5. Left side of a cast of the interior, X 3. 
6 and 7. Left side and anterior views of same, natural size. 
Figs. 810, Cyfricardites terminalis, n. sp. 
8. A left valve from the limestone at Minneapolis, natural size. No. 
5,100 of the Mus. Reg. of the Geol. and Nat. Hist. Surv. of Minnesota. 
9. A right valve from a similar position at Cannon Falls, Minnesota. 
10. Anterior view of these two valves. 
Figs. 11 and 12, Technophorus pilistriatus, n. sp. 
A left valve, natural size, and the antero-basal portion, X 3, to show 
concentric lines. 
Figs. 13 and 14, Technophorus subacutds, n. sp. 
13, Cast of a left valve, natural size. 
14. The same, nearly X 3.5, with the impression of the hinge and in- 
ternal ridge. 
Figs. 15 and 16, Technophorus divaricatus, n. sp. 
A left valve of the natural size and X 3. 
Fies. 17 and 18, Tellinomta longa, n. sp. 
Interior views, of the natural size and X 3, of a right valve. 
