TRENTON LIMESTONE. 
313 
149. 12. LEPT7ENA DEFLECTA. 
Pl. XXXI. B. Figs. 5 a, b. 
Strophomena deflecta. Conrad, Proc. Acad. Nat. Sci. Philadelphia, 1843, Vol. i. p. 332. 
Resupinate, semioval; dorsal valve slightly concave and elevated towards the beak, 
deflected at the angles ; ventral valve moderately convex ; cardinal extremities reflected ; 
cardinal area wide, partially common to both valves ; foramen partially closed ; surface 
marked by fine equal striae which are crossed by fine elevated concentric lines, giving the 
striae a crenulated appearance. 
This is a robust, very symmetrical shell, bearing a close analogy to the L. Jilitexta 
( fig. 3), from which, however, it is apparently distinct. The striae are more distinctly 
crenulated, sharper, and more elevated than in that species ; though for want of a sufficient 
number of specimens, and a knowledge of the internal structure of the shell, I still feel 
some hesitation in regard to its distinctive character. A single specimen, only, has been 
examined, the prominent characters of which are the nearly flat dorsal valve, with elevated 
beak and sharply crenulated striae. 
Fig. 5 a. Dorsal valve of the specimen. 
Fig. 5 b. Cardinal area of the same. 
Position and locality. This species occurs at Mineral Point ( Wisconsin) , associated with 
numerous other well known Trenton species, leaving no doubt of its true geological 
position.* 
* ■ ** 
150. 13. LEPTflENA RECTA. 
Pl. XXXI. B. Figs. 6 a, b. 
Strophomena recta. Conrad, Proc. Acad. Nat. Sci. Philadelphia, 1843, Vol. i. p. 332. 
Semioval, nearly semicircular, compressed ; cardinal line very straight, extending beyond 
the width of the shell, and angulated at the extremities ; area narrow, equally common to 
both valves ; ventral valve scarcely convex, with a slight mesial depression ; dorsal valve 
flat, elevated towards the beak ; surface marked by strong bifurcating crenulated stria;. 
The specimen under examination has perhaps suffered some distortion, but it is remarkable 
for the nearly equal areas, and the almost entire flatness of both valves. In its angulated 
and extended cardinal extremities it resembles the succeeding species ; but that shell is 
much longer in proportion to its width, and the striae are less sharply crenulated. 
* Mr. Conrad has kindly placed this and some other western specimens at my disposal, for the purpose of instituting 
a comparison between the eastern and western species of our lower formations. 
[ Paleontology.] 15 
