1878.] 21 [Rathbun. 
able that we have more than a single species included in Chonetes 
Herbert-Smithiit, as originally founded. Much of the material at 
hand is in an imperfect state of preservation, the majority of the 
specimens, however, belonging to the type as first described. Thus it 
does not seem advisable to make a division of the species, until other 
and better material has been obtained. 
Moderately abundant in the Devonian sandstone of Ereré. (Mor- 
gan Exs., 1870 and 71; Geol. Comm., 1876.) 
Chonetes curuaensis, sp. nov. 
Shell small and transverse, with the proportions of length to 
breadth about as 2 to 3; in outline longitudinally sub-semielliptical, 
the lateral margins being nearly straight posteriorly, and not curving 
much, excepting toward the front. Hinge line straight and nearly or 
quite as long as the width of the shell, which has the cardinal ex- 
tremities forming right angles or, probably, slightly rounded. 
Ventral valve gently convex and most elevated near the middle, 
but having the convexity slightly more pronounced on the umbonal 
region than toward the front of the valve. Curve along the trans- 
verse diameter gentle and nearly regular, though the sides of the valve 
appear to slope from the median line to the lateral margins with little 
curvature. Cardinal extremities flattened. Beak small, but dis- 
tinctly marked, slightly depressed and projecting only a short dis- 
tance behind the hinge line. ‘There is a small, well-defined septum, 
extending forward from the beak a little more than one-fourth the 
shell length. Hinge area and spines not preserved. Surface 
marked with fine, but prominent, subangular, radiating raised lines, 
which are slightly narrower than the intervening depressions. 
There are about twenty-six of these lines on one ventral valve, on 
which, however, the cardinal extremities are smooth; there also exist 
one or two rather prominent, concentric lines of growth. Length of 
valve about 6 mm., breadth 9 mm. Dorsal valve unknown. 
This species of Chonetes, which is represented by only a single 
perfect specimen, bears some resemblance to C. Herbert-Smithii of 
the Ereré locality, from which, however, it differs in the fact that the 
ventral valve of the former is less strongly convex, and has a more 
prominent beak and finer surface markings. It also resembles some- 
what the young of C. Freitas of the Rio Mecurt locality. From 
C. scitula Hall, of the Hamilton group of New York State, which 
it resembles much in form, it differs in having fewer and coarser 
raised lines. Only a few specimens of this species have been found. 
