Bracuiopopa. | LOWER PALAOZOIC MOLLUSCA. 258 
LINGULA LATA (Sow.) 
Ref:.—Sow. Sil. Syst. t. 8. f. 1]. 
Sp. Ch.—Ovato-oblong, moderately and evenly convex ; lateral margins gently convex, subparallel, gradually 
passing into the posterior lateral margins, which are more convex, and converge to form an obtuse, semielliptical, 
posterior end; front margin obtuse, slightly convex and a, little narrowed; surface usually white, marked with 
minute lines of growth. Length three lines and a half, proportional width 2. 
This little species is shorter and wider than the Z. cornea, which it most resembles, and has more conyex 
margins. 
Position and Locality.—Very common in the olive Ludlow rock of Mortimer’s Cross, Aymestry, Here- 
fordshire ; Upper Ludlow rock of Woolhope. Very abundant of small size in some layers of the Lower 
Ludlow sandstone of Leintwardine, Shropshire. 
LINGULA LEWISII (S07.) 
Ref.—Sow. Sil. Syst. t. 6. f 9. 
Sp. Ch.—Longitudinally oblong, subquadrate, with a flattened tumidity along the middle, gradually arching 
to the front margin, the sides abruptly sloping from the beak in a nearly straight line to the front lateral angle 
on each side; sides straight, parallel; front margin subtruncate, slightly rounded; posterior lateral margins 
straight, slightly more than half the length of the sides, with which they form an obtuse angle, converging to 
the obtuse beak at an angle of about 120°; surface with minute, irregular, concentric wrinkles and strize of 
growth, and on the front a few broad, obtuse, radiating ridges (about five in the space of two lines) near the 
margin. Average length ten lines, proportional width % to 5, depth 3. 
The front of this species is more truncate, and the radiating mesial ridges much fewer, wider, and farther 
apart, than in the LZ. quadrata of the lower beds of Russia and North America, with which it has been 
confounded. 
Position and Locality—Common in the Aymestry limestone of Sedgley, near Dudley, Staffordshire ; olive 
Caradoc shale of Cheney Longville, Shropshire ; Lower Ludlow rock of Leintwardine, Shropshire. 
LINGULA LONGISSIMA (Pander). 
Ref—Pander, Beitrage, &e. t. 3. f. 21. Geol. Russ. t. 1. f, 11. Kutorga, Verhand. der Russ. Kaiserl. 
Min. Gesell. zu St. Petersburg, t. 7. f. 3. 
Sp. Ch.—Very elongate, ovate ; sides subparallel, very slightly convex, gradually passing into the slightly 
narrowed, blunt, elliptically rounded front, and more gradually into the narrower elliptically pointed posterior 
end; both valves very convex, rising evenly from the margins all round (not flattened) ; greatest depth about the 
middle of the length ; cast of internal mesial ridge very long, reaching to within one-sixth of the length of the 
front margin ; external surface with very minute, close, fine, concentric wrinkles, and internal casts with faint 
traces of obsolete, rather coarse, longitudinal striz in the middle. Length three lines, proportional width 3, 
depth =. 
Although neither of the above writers mention the traces of longitudinal striz on the internal cast, there 
cannot be the slightest doubt in the identification of this species, rendered so distinct by its very narrow, ovate, 
tumid form. 
Position and Locality.—In the Bala limestone, Mynydd Fron Frys, five miles W. of Chirk, N. Wales. 
LinetLa optusa (fall). 
Ref—Hall, Pal. New York, t. 30. f. 7. 
Sp. Ch.—Longitudinally ovate, very gibbous near the beaks which are obtusely rounded, the convexity 
extending for a narrow space about half the length of the shell, becoming much depressed and flattened towards 
