OSTRACODA. 663 
Eurychilina subaquata. ] 
EurYCHILINA ? SUBEQUATA, 2. Sp. 
PLATE XLV, FIGS. 7—9. 
SizE.—Without border, length 1.55 mm.; hight 0.85 mm.; thickness 0.58 mm. 
With border, length 1.80 mm.; hight 1.05 mm. 
Valves quadrate-subelliptical in outline, strongly convex, with the dorsal angles 
obtuse, the ends rounded, and the dorsal and ventral margins nearly parallel. Body 
of valve rather uniformly convex, with the anterior end a trifle more obliquely 
rounded than the posterior. Sulcus situated a little behind the center, deep, narrow, 
beginning at the straight dorsal border and terminating abruptly ata point less than 
one-third of the hight of the valve beneath it. On each side of the sulcus the surface 
rises into a low eminence, one, supposed to be the posterior, a little higher than the 
other. Central portion of surface exhibiting numerous, rather irregularly distribu- 
ted pustules. Border not defined by an impressed suture line, flattened except at its 
extreme outer edge where it bends suddenly inward. Its surface presents more or 
less obscure radial series of minute granules, most distinct on the. ventral portion 
where the border is also the widest. 
As stated under the generic description, this is one of a number of species 
belonging to an undescribed genus. Of these forms L. ? striatomarginata Miller, 
from the uppermost beds of the Cincinnati formation, and LH. ? obesa Ulrich, from 
the Birdseye limestone of Kentucky, are probably the nearest. The first is less 
convex, has a different sulcus and a wider border, marked with fine radiating lines 
instead of rows of granules. The latter agrees very well in most respects but may 
be distinguished at once by the absence of any well defined sulcus. 
Formation and locality.— Upper third of the Trenton shales (Phylloporina bed), St. Paul, Minnesota. 
EKuURYCHILINA ? SYMMETRICA, 2. Sp. 
PLATE XLIV, FIGS. 5—7. PLATE XLY, FIGS. 4—6.. 
Size.—Length 1.8 mm.; hight 1.1 mm.; thickness 0.4 mm. 
Length 1.7 mm.; hight 1.08 mm. 
Valves subelliptical or somewhat quadrate, equilateral, greatly compressed, 
1.6—2.0 mm. in length. Dorsal margin straight or slightly convex, a little shorter 
than the valve; dorsal angles not very sharp; ventral margin semielliptical, curving 
neatly into the rounded ends. Body of valve flattened, but rising at two points near 
the hinge, each situated about midway between the dorsal angles and the center, 
into two, more or less prominent, large subequal rounded tubercles. These are 
connected by a thin ridge, the two bulbs and connecting bar resembling the old “bar 
shot,” Surface bicadly excavated centrally, and marked with obscure pits. Marginal 
