OOLITIC BIVALVES. 
99 
A. vaghiula differs from this Trias species— (A. triassica, 
Stopp., 1. c. pi. 16, f. 17) in being only half the proportional 
length. Ours was sixteen lines long when a perfect shell, and 
full half an inch broad at the beak. 
The anterior side [is lost]. The posterior end is regularly 
attenuate, and rather quickly sloping beyond the hinge line 
on the dorsal margin, which, however, is not much curved : 
a faint oblique ridge or two occur beneath it, but only on the 
posterior slope ; and there appear to be no internal radiating 
ridges, as in the Alpine form. A. precursor, Stoppani, is a 
curved species, and does not need close comparison. 
TEREBRATULA NUMISMALIS- — Lam . 
Plate 28, fig. 4. 
Lamarck, Anim. sans Vert., 1819, vol. vi., No. 22. 
T. orbicularis, Zieten, 1832. Verst., Wurtemb., pi. 39, f. 5. 
T. numismalis, Bronn; Von Buch; Quenstedt; D’Orbigny; David¬ 
son, &c. 
T. cor. Valenciennes. 
Our single specimen agrees well with ordinary specimens 
from the English Marlstone, except in being a little more elong¬ 
ate, and the beak rather more prominent. It has the char¬ 
acteristic ridges of growth, which are not very well shown 
in Davidson's figures. 
T, C ARIN AT A —L ‘ marck. 
Plate 21, fig. 5. 
Compare with T. resupinata, Sow.; T. Moorei, Davidson; T. em° 
nrginata , Sow.; and T. impress a. Von Buch—in Davidson’s Monogr. 
of Oolitic Brach., Pal. Soc., 1852, pi. 4. 
Our artist has omitted the most important character of this 
shell, viz., the depression of the upper valve upon the front 
margin. A narrow, but rather deep sinus, hidden from sight 
