682 THE PALEONTOLOGY OF MINNESOTA. 
{Moorea angularis. 
MoorEA ANGULARIS, ”. Sp. 
PLATE XLIII, FIG 89, PLATE XLVI, FIGS. 15—16. 
Sizz.—Length 0.67 mm.; hight 0.40 mm.; thickness 0.23 mm.; length of hinge line 0.65 mm. 
Valves compressed, suboblong, slightly leperditoid in outline, the posterior end 
a little wider than the anterior; hinge line straight, nearly or quite as long as the 
greatest length of the valve, with the dorsal angles acute; beneath them the outline 
is nearly semicircular; ridge thin, almost marginal, strongest ventrally, wanting or 
scarcely distinguishable dorsally; surface smooth, nearly flat. 
Two specimens only have been seen of this species. Both are figured, the one 
from Minneapolis on plate xii, the other, from Fountain, on plate xtvr. The latter 
is the larger of the two and differs from the other, which is to be regarded as the 
type, in several respects. Possibly it is distinct, but asit has evidently suffered from 
weathering or maceration, the differences may not be normal, hence I perfer for the 
present to classify it as an imperfect valve of M. angularis. 
The almost flat, though thick-edged valves of this species, cannot be mistaken, so 
that comparisons are quite unnecessary. 
Formation and locality—Middle third (Rhinidictya bed) of the Trenton shales, Minneapolis, and 
near Fountain, Minnesota. 
MoorEA PUNCTATA, 2: Sp. 
PLATE XLIII, FIGS. 84—88. 
Sizz.—Length 0.40 mm.; hight 0.24 mm.; thickness 0.18 mm. 
Length 0.50 mm.; hight 0.32 mm.; thickness 0.22 mm. 
Valves somewhat oblong-quadrate, the hinge nearly straight, about one-fifth 
shorter than the greatest length of the carapace; dorsal angles distinct; ends sub- 
equal; not strongly rounded, sometimes obliquely truncate above; marginal ridge 
developed along the anterior, ventral and posterior borders, thinnest and least 
prominent ventrally, thickest and somewhat club-shaped posteriorly, the ends 
terminating abruptly before reaching the dorsal angles; ridge usually continuous, 
but occasionally incomplete ventrally. Within the ridge the surface is flat and 
minutely punctate; above it descends abruptly to the hinge line. 
A neat little species, reminding considerably of Placentula excavata Jones and 
Holl, and of species of Bollia like B. vinei J. and H., or B. subequata. It is smaller 
than Moorea angularis, has less pronounced dorsal angles, a punctate surface, and 
different marginal ridge. 
Formation and locality.—Upper third (Phylloporina bed) of the Trenton shales, St. Paul, Minnesota. 
