DEVONIAN FAUNAS. 309 
from five to eight plications are included in mesial sinus and a cor- 
responding number on the fold of the brachial valve. 
The dimensions of an average specimen are, approximately: length, 
17 mm.; width, 19.5 mm. 
Remarks.—This species may be distinguished from most of the 
other Rhynchonelloid shells in the Helderbergian faunas of New Jer- 
sey by its much finer plications. The only other species with as fine 
plications is U. mutabilis, from the Coeyman’s limestone, but the sub- 
globose form of that species will easily distinguish it from U. velli- 
catus. The species is usually poorly preserved in New Jersey, and 
occurs, for the most part, in the upper portion of the New Scotland 
beds or the Becraft limestone. 
UNCINULUS PYRAMIDATUS (Hall). 
Plate XXXVI., Figs. 8-11. 
See, also, p. 285, pl. XXIX. 
This shell attains a much larger size in the fauna of the New Scot- 
land beds than in the Coeyman’s limestone, and is also a much com- 
moner species. 
RHYNCHOTREMA FORMOSA (Hall).? 
Plate XXXVIJI., Figs. 12-15. 
See, also, p. 328. 
1859. Rhynchonella formosa Hall, Pal. N. Y., vol. IIL, p. 236, pl. 
35, figs. 6 a-y. 
Description.—Shell subrhomboidal in outline, wider than long. 
Pedicle valve convex on the umbo, from which point the surface curves 
abruptly to the cardinal and gently to the lateral margins, depressed 
toward the front in a deep and sharply-defined mesial sinus, which is 
produced in front. Brachial valve more convex than the pedicle, 
greatest elevation at the anterior margin, with a prominent median 
fold beginning at the middle of the valve and continuing to the front. 
Surface of each valve marked by from sixteen to eighteen simple, 
angular, radiating plications, of which three occupy the mesial sinus 
of the pedicle valve and four the fold of the brachial valve. 
