LAMELLIBRANCHIA TA. 
437 
Lunulicardium curtum. 
PLATE LXXX, FIGS. 18-23. 
Lunulicardium curtum, Hall. Prelim. Notice Lamellibranchiata, 2, p. 97. 1870. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 71, fig’s. 18-23. 1883. 
Shell below the medium size, ovate, sub-trigonal; length usually a little less 
than the height. Anterior and basal margins regularly curving. Entire 
length of the posterior side truncate, with a narrow alation along the margin. 
Valves, in well-preserved specimens, regularly convex below, becoming- 
gibbous in the middle and above. 
Beaks anterior to the middle, prominent, incurved and directed forward. 
Surface marked by from twenty-five to thirty regular, narrow, rounded or 
sub-angular plications, with wider interspaces, and by fine lamellose concen¬ 
tric striae, which arch upward on the plications. Some specimens show a 
pustulose character of the surface as indicated in fig. 23 of plate lxxi. 
Three specimens measure respectively 13, 20 and 23 mm. in length, and 
14, 18 and 24 mm. in height. 
This species differs from L. rude in its greater height, larger number of plica¬ 
tions and more delicate characters. As compared with L. ornatum, it has a pro¬ 
portionally much longer posterior truncation, and fewer and narrower plications. 
Formations and localities. In the Marcellus shale at Alden, Erie county, N. Y., 
and in the Hamilton shales on the shores of Cayuga and Seneca lakes, and at 
Pratt’s falls, Tully and Hamburg, N. Y. 
Lunulicardium ornatum. 
PLATE LXXI, FIGS. 25-32. 
Pinnopsis ornatus, Hall. Geol. Surv. N. Y., Rep. Fourth Dist., p. 244, t. ISO, fig-. 8. 1843. 
Lunulicardium ornatum, Hall. Prelim. Notice Lamellibranchiata, 2, p. 97. 1870. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 71, figs. 25-29. 1883. 
Pinnopsis acutirostra, “ Geol. Surv. N. Y., Rep. Fourth Dist., p. 244, t. 106, fig. 7. 1843. 
Lunulicardium acntirostrum, Hall. Preiim. Notice Lamellibranchiata, 2, p 97. 1870. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 71, figs. 30-32. 
Shell large, broadly obovate, truncate upon the posterior side. Anterior and 
basal margins regularly rounded, recurving abruptly at the posterior. 
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