DEVONIAN FAUNAS. 327 
median line, lateral slopes nearly straight; beak rather small, in- 
eurved over the narrow cardinal area. Brachial valve depressed- 
convex on the umbo, flattened laterally, depressed medially in a 
shallow, ill-defined sinus, which broadens rapidly toward the front. 
Surface of both valves marked by numerous, fine, angular, radiating 
coste, which increase by bifurcation and which become more and 
more strongly curved as they approach the cardinal margins. The 
radiating markings are crossed by much finer concentric strie, which 
have usually been entirely obliterated on the New Jersey specimens. 
The dimensions of a pedicle valve are: length, 15 mm.; width, 
17 mm.; convexity, 5 mm. 
Remarks.—This species is closely allied to R. perelegans, but is a 
smaller shell, with the brachial valve much- more flattened and the 
pedicle valve more sharply carinate. 
DALMANELLA PERELEGANS (Hall). 
See, also, p: 305, pl. XCXXXV- 
A few specimens in the “trilobite bed” seem to represent this species, 
which is more abundant in some of the older beds. They are asso- 
ciated with D. subcarinata, which is much the commoner form, but 
differ from members of that species in their larger size and less 
sharply-carinate pedicle valve. The only specimens observed are frag- 
mentary, and do not at all perfectly represent the species. 
RHYNCHONELLA BIALVEATA Hall. 
Plate XLII., Figs. 9-10. 
1859. Rhynchonella? bialveata Hall, Pal. N. Y., vol. I11., p. 233, pl. 
34, figs. 1-4. 
Description.—Shell small, elongate, subtrigonal or subovate in out- 
line; postero-lateral margins converging toward the beak at an angle 
of 55° to 65°. Pedicle valve moderately convex; surface rather 
abruptly curved to the postero-lateral margins, the median portion 
depressed anteriorly in an ill-defined, shallow sinus, which reaches 
