244 BRITISH PALAXOZOIC FOSSILS. [ Bracuiopopa. 
close to the beak; general surface very coarsely punctate, and marked, especially near the margins, with the 
external radiating strie. Width (of small specimen) nine lines, proportional length =, depth =. 
I am doubtful of the genus of this very interesting shell, from not having clearly seen the cardinal 
area: it is extremely analogous in general form, and the character of the striation (the latter not well 
represented in Sowerby’s figure), to the Orthis expansa, including the alternata of Sow.; but the large lines 
arch less on the sides, the whole striation is considerably finer, and the species is completely distinguished 
from that of the older rocks by the very long dental lamelle of the receiving valve, and the very small 
angle at which they diverge, creating a total difference in the muscular impressions. In old specimens the 
strize become coarse and more equal, with the interspaces very coarsely punctured. 
Position and Locality —Abundant in the Upper Ludlow rock of Tulithwaite Hall, Underbarrow, Kendal, 
Westmoreland; doubtful specimens in the olive schists above the second grits of Keeper’s Lodge, Golden- 
grove, Llandeilo; Aymestry limestone of Sedgley, near Dudley, Staffordshire; Upper Ludlow rock of Burton 
and Brockton, near Wenlock. 
LertTana (Strophomena) FUNICULATA (M°Coy). 
Ref. and Syn. = Orthis funiculata M°Coy, Sil. Foss. Irel. t. 3. f. 11. 
Leptena id. Davidson, Lond. Geol. Journ. t. 12. f. 6 to 8. 
Sp. Ch.—Semicircular, twice as wide as long ; entering valve flattened, slightly convex towards the beak, 
slightly concave about the middle, and abruptly deflected nearly at right angles, to form a narrow border 
at the margin, the angle obtusely rounded ; hinge-line slightly exceeding the width of the shell; ears acute ; 
cardinal area narrow, triangular in the receiving valve, linear in the entering valve; pseudo-deltidium very 
small; surface radiated with obtuse, cord-like striz, usually less than half their thickness apart, frequently 
dichotomising, but remaining nearly uniform in size over the whole shell, nine or ten in two lines, at four 
lines from the beak, crossed by fine strize of growth; internal cast of receiving valve with two large longitu- 
dinally ovate or triangular, flattened, slightly elevated marks of the muscular impressions, extending nearly 
three-fourths the length of the flattened rostral portion, flanked by two long, slightly incurved dental lamellee 
diverging at 60°; a very slender impression of a linear mesial septum divides the muscles; internal cast of 
entering valve with two thick diverging pits, produced by the lateral lobes of the irifid rostral tooth; from this 
a deep impression of an obtusely rounded mesial septum extends about half the length of the flattened rostral 
portion, flanked on each side by two obtusely rounded, slightly incurved furrows, from corresponding ridges on 
the valve; the rostral portion of the inner surface of both valves is spinulose, the angle and deflected front 
marked with punctured striz. Width ten lines, proportional length of flattened rostral portion 4, deflected 
front 3; 
The close, obtuse, sub-uniform strize easily distinguish this species from dwarf examples of the S. euglypha, 
with which I understand some observers have confounded it. The bilobed boundaries of the muscular 
impression in the concave or receiving valve are longer and narrower than in the S. euglypha. 
Position and Locality—Common in the Wenlock limestone of Dudley, Staffordshire; common in the 
schists above white grits, Parklane, Ludlow, Shropshire; one doubtful fragment in the Bala schists of Cyrn y 
Brain, Wrexham, Denbighshire. 
LePTANA (Strophomena) GRANDIS (Sow. Sp.) 
Ref. and Syn. = Orthis grandis Sow. t. 20. f. 12 and 18. 
Sp. Ch.—Truneato-elliptical, varying considerably in proportional length; hinge-line equalling or slightly 
exceeding the greatest width; cardinal angles slightly pointed; receiving valve very slightly convex near the 
beak, which is rather prominent, gently concave about the middle, and flattened along the margins, which 
are flattened, horizontal, or with a very faint wave towards the entering valve ; cardinal area low, triangular, 
about twelve times wider than high, inclined backwards at about 130°; cardinal opening partially closed by 
a pseudo-deltidium ; dental lamelle slender, diverging at 105° (less in one specimen), slightly incurved at their 
