Rathbun.] 30 [May 15, © 
valve. Itis regularly rounded from side to side, but on the anterior 
half it is marked with two longitudinal, shallow and narrow, but de- 
fined depressions, giving it there a three-lobed character. In one 
specimen the central lobe is slightly broader than the laterals; in an- 
other the central lobe is the narrower. On each side of the fold are 
eight simple, rounded plications, separated by slightly narrower, 
rounded depressions, the plications growing successively smaller in 
size toward the sides, and the more lateral ones bending slightly out- 
ward as they extend from the hinge line toward the margin. The 
plications are not very distinctly marked on the posterior part of the 
valve. Only two dorsal valves of this species are known. The larger 
is imperfect, but the smaller has the following dimensions; length 
21 mm., breadth 33 mm., depth of dorsal valve 5.6mm. Ventral 
valve unknown. 
This species of Spirifera is readily distinguished by the three-lobed 
character of the dorsal median fold. In all of the other Devonian 
species from Brazil, the median fold is simple. 
Devonian sandstone, Rio Mecurt. (Geol. Comm., 1876.) 
Spirifera meecuruensis, sp. nov. 
Shell minute, gibbous, with rounded cardinal extremities, and 
about four low, broad, rounded plications on the ventral valve. 
Ventral valve very convex; length and breadth about equal; in 
outline forming obliquely a nearly square figure, but with the ante- 
rior margin of the shell slightly rounded. The surface arches strongly 
upward from the front, along the median line, to a point a short dis- 
tance back of the middle of the valve, whence it curves slightly 
downward to the beak. Beak large and prominent, and much ex- 
tended behind the hinge line, but only slightly ineurved. Hinge 
area broad, triangular and very slightly concave; inclining strongly 
forward from the beak, so as to form an angle of about 110° to 120° 
with the plane of the shell margins. The distance from the hinge 
line to the beak is equal to nearly one-third the entire length of the 
valve, and in the triangular figure formed by the hinge area, the base, 
represented by the hinge line, is equal to about one and one-half 
times the length of each of the other two sides. Cardinal margins 
not sharply defined, the surface curving rapidly over from the hinge 
area into the general surface of the valve. Length of the hinge line 
equal to nearly two-thirds the width of the valve; cardinal extremi- 
ties regularly rounded; fissure large, triangular, but widening only 
gradually from the beak toward the hinge line, where its width is 
