OSTRACODA. 663 



JB-urychihna sabEequata.] 



EURYCHILINA ? SUBjEQTJATA, tl. 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.; bight 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 at a 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 E. ? striatomarginata Miller, 

 from the uppermost beds of the Cincinnati formation, and E. ? ohesa 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 abse-nce of any well defined sulcus. 



Formation and iocaHfj/.— Upper third of the Trenton shales (Phylloporina bed), St. Paul, Minnesota. 



EuRYCHILINA ? SYMMETRICA, W. Sp. 

 PLATE XLIV, FIGS. 5—7. PLATE XLV, 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 broadly excavated centrally, and marked with obscure pits. Marginal 



