LAMELLIBRANCHIA TA . 
301 
above the hinge-line. Umbo moderately prominent. Umbonal ridge dis¬ 
tinctly angular, extending from the beak to the post-basal margin. 
Test thin, marked by fine concentric striae, which are more or less fascicu¬ 
late on the body of the shell, and very regular and uniform on the post- 
cardinal slope. Interior unknown. 
The right valve in the specimen figured on plate lxv, fig. 20, has a length 
of 49 mm. and a height of 19 mm. A larger and better-preserved specimen 
has a length of 59 mm. and a height of 22 mm. Another specimen referred 
to this species has a length of 45 mm. and a height of 18 mm.. 
This species differs from the others of the Hamilton group in its narrow ellip¬ 
tical form, the regular curving basal margin, and narrow anterior end. The 
hinge-line is comparatively shorter than in any of the species of the Hamilton 
group except G. truncata. 
Formation and localities. In the upper portion of the Hamilton group, at 
Geneseo, Livingston county ; at Bellona, Yates county ; on the shore of Cayuga 
lake, and from a boulder of Hamilton shale at Sexton’s, near the head of Seneca 
lake, N. Y. 
Goniophora carinata. 
Plate xlii, fig. ii ; and plate xliv, figs. g-s. 
Cypricavdites carinata, Conrad. Geol. Surv. N. Y., Ann. Rep., p. 53, plate, tig. 21. 1841. 
iSanguinolites carinatus (Conrad), Hall. Prelim. Notice Lamellibranchiata, 2, p. 43. 1870. 
Compare Oypricardites Chemungensis, Vanuxem. Geol. Surv. N. Y., Rep. Third Dist., p. 181, 2; p. 179. 
1842. 
Shell of medium size or larger, trapezoidal; length more than twice the height; 
basal margin sinuate anterior to the middle, curving gently to the post-basal 
extremity and more abruptly to the anterior; posterior margin oblicpiely 
truncate. Cardinal line nearly straight and parallel with the basal margin, 
equal to one-half the length of the shell. Anterior end sloping gently from 
the beak and abruptly rounded below, limited by a broad undefined sinus 
which constricts the basal margin. 
Valves moderately convex below the umbonal ridge, slightly concave on 
the cardinal slope. 
39 
