644 THE PALEONTOLOGY OF MINNESOTA. 
[Aparchites ellipticus. 
APARCHITES ELLIPTICUS, ”%. Sp. 
PLATE XLIII, FIGS. 15—17. 
Size.—(E. C.) Length 1.97 mm.; hight 1.35 mm.; thickness 0.95 mm. Inthe largest specimen the 
length is 2.5 mm, 
Carapace rather large for the genus, almost regularly elliptical in outline, the 
dorsal margin of the left valve more arcuate and projecting above that of the right; 
edges beveled all around but in the lower part the bevel is turned into a groove by 
the thickening of the contact edges; surface of valves smooth and rather uniformly 
convex. 
This form, though the hinge is shorter than usual, must still be considered as a 
typical species of the genus. The general expression of the carapace is much as in 
the associated Leperditella persimilis, but it is somewhat longer, has no dorsal angle, 
and its valves do not overlap. I know of no American species of Aparchites with 
which it need be compared, the elliptical outline being distinctive, but there are 
several in the Upper Silurian deposits of Europe that are not far removed. Particu- 
larly is this true of the A. simplex, from Gothland, described by Prof. Jones in the 
Ann, and Mag. Nat. Hist., ser. 6, vol. iv, p. 272, That species, however, is smaller 
(0.9 mm. in length), relatively shorter, and apparently without bevelled edges. Some - 
of the varieties referred to A. (Primitia) maccoyii Jonesand Holl, are very near, if not 
identical. But I am not willing to admit the latter without a direct comparison of 
specimens, 
Formation and locality.—Middle third of the Trenton shales, Minneapolis, Minnesota. An imper- 
fect left valve from the Galena shales near Cannon Falls, may belong to this species, but it appears to 
have been relatively longer and somewhat narrower anteriorly. 
APARCHITES GRANILABIATUS Ulrich. 
PLATE XLY, FIGS. 21—23. 
Leperditia granilabiata ULRICH, 1892. American Geologist, vol. x, p. 267. 
Sizz.—(L. V.) Length 2.1 mm.; hight 1.5 mm.; thickness 0.6 mm. 
Valves high, very little oblique, ventricose in the lower half, somewhat flattened 
in the upper; outline almost semicircular in the lower two-thirds, the ventral curve 
being unusually convex; dorsal margin straight, about three-fourths as long as the 
valve, with angular extremities; border scarcely defined, set with small but promi- 
nent papille; free edges bevelled strongly inward. Surface covered with minute, 
regularly arranged granules; near the center a small raised spot.* 
Recent comparisons have demonstrated the necessity of excluding species of this 
type from Leperditia. They have shown further that the typical species of Aparchites 
*In the original description the surface is incorrectly described as punctate. 
