122 
Semielliptical, very convex; hinge line somewhat longer than 
the width of the valves; margin slightly deflected; lower valve 
greatly and regularly convex, the other nearly equally concave; 
the whole surface concentrically wrinkled, but almost obsolete 
near the disk; with adpressed spines, those contiguous to the 
hinge line considerably elongated. 
Found in the Devonian Shales at Petherwin, Barnstaple, and 
Croyde. 
3. Leptcena sordida —The Dilapidated Leptama, pi. 
LIII.* fig. 19. 
Leptcena sordida . Sowerby, Geo. Trans. V. 2nd series, pi. 
53, fig. 5 and 16. 
Transversely elongated, somewhat convex; hinge line not 
quite equal to the breadth of the valves, with rounded angles; 
surface irregularly striated; muscular impressions occupying 
nearly half the internal area. Variable in width, sometimes 
almost orbicular, at others its width nearly double its length. 
Carboniferous Limestone, Tenby; Devonian Limestone, 
Linton and Torquay; and the Upper Ludlow Rocks, West¬ 
morland. 
4. Leptcena fragauia —The Rough Leptama, pi. LIV. 
fig. 9. 
Leptcena fragaria . Sowerby, Geo. Trans. V. 2nd series, 
pi. 54, fig. 3, and pi. 56, fig. 5, 6. Phillips, Pal. Fos. p. 59, pi. 
25, fig. 100. 
Nearly hemispherical, with the sides slightly produced; beak 
of the convex valve subacute; hinge line somewhat shorter than 
the width of the valves; surface concentrically undulated, almost 
smooth, and pustulated. 
Found in the Devonian Shales at Plymouth and Petherwin. 
5. Leptcena rugosa. —The Rugged Leptcena, pi. LIV. 
fig. 36. 
Leptcena rugosa . Sowerby, Geo. Trans. V. 2nd series, pi. 
56, fig. 4. Phillips, Pal. Fos. p. 57, pi. 24, fig. 95. 
Semicircular; hinge line prolonged into two short, auriform 
processes; lower valve a little convex, and bent upwards on the 
edge to meet the upper valve; surface with regular, concentric 
wrinkles; border provided with rounded undulations, crossed by 
numerous, equal, straight, filiform striae. Length one inch. 
Found in the Devonian Shales at Plymouth and Newton 
Bushel; and in the Lower Silurian Rocks at Coniston. 
6. Lept/ENa przelonga. —The Lengthened Leptaena, pi. 
LIII. fig. 62, 63. 
Leptcena prcelonga. Sowerby, Geo. Trans. V. 2nd series, 
pi. 53, fig. 29. 
Transversely obovate, convex, with a central furrow; beak of 
larger valve ventricose, and overhanging that of the smaller one, 
which is concave; margin considerably deflected; hinge line 
shorter than the width of the shell, from which emanate a few 
concentric undulations; whole surface with coarse, irregular, 
transverse striae. 
Found in the Devonian Shales at Croyde Bay. 
7. Lept/ena reticulatus. —The Reticulated Leptaena, 
pi. LIII. fig. 53, 54. 
Spirifera ? crenisMa. Sowerby, Geo. Trans. V. 2nd series, 
pi. 57, fig. 7. 
Subovate, subcompressed; hinge line parallel, extending the 
entire breadth of the valves; sides nearly straight; base round¬ 
ed ; whole surface covered with strong, divergent stria), and 
LEPTiENA. 
crossed by concentric, less decided stria), giving it a finely 
reticulated aspect. 
Mountain Limestone, Matlock, Derbyshire. 
8. Leptzena Lepisma —The Silvery Leptama, pi. LIII.* 
fig. 25. 
Leptcena Lepisma . Sowerby, Sil. Syst. p. 618, pi. 8, fig. 7. 
Semicircular, convex, with a shining, silvery, or satin-like 
lustre; surface with a few obscure, slightly elevated, forked 
radiations, and indistinctly punctated; hinge line as wide as the 
shell; base moderately deflected. Length nearly three lines; 
breadth five lines and a half. 
Lower Ludlow Rock, near Clangunford. 
9« Leptzena euglypha. —The Well-carved Leptama, pi. 
LIII. fig. 28. 
Leptcena euglypha . Dalman, Act. Holm. 1827, p. 118, pi. 
1, fig. 3. Ib. Hist. Pet. Suec. pi. 20, fig. 4. Sowerby, Sil. Syst. 
p. 618 and 623, pi. 12, fig. 1. Or this euglypha , Von Buch. 
Subtriangular; base obtuse; flat above; hinge area long, 
straight, and narrow; surface covered with numerous, radiating, 
slender ridges, with intermediate, fine, elevated stria). Length 
of flat space one inch; width two inches and a half; depth in 
front at base one inch. 
This species is liable to considerable variation in form: the sides in 
some specimens being considerably less flattened than in our figure; the 
intermediate striae sometimes as large as the ridges; and the sides at the 
hinge line shooting out to extended angles; the striae are also frequently 
like those of Orthis alternata. 
Wenlock Limestone at Aston, near May Hill, Daley; Fawn- 
hope ; Abberley and Wigmore. 
10. Lepta-.na depuessa —The Depressed Leptama, pi. 
LIII* fig. 29, 30, 31. 
I^eptcena dejjressa . Dalman, 1. c. p. 106, pi. 1, fig. 2. Ib. 
Hist. Pet. Suec. p. 69, pi- 20, fig. 3. Sowerby, Sil. Syst. p. 
623, pi. 12, fig. 2. Producta depresses Sowerby, Min. Conch. 
V. pi. 459, fig. 3. 
Nearly semicircular, depressed above, with strong, longitudi¬ 
nal stria), which are interrupted by transverse, wide-set, narrow 
furrows; hinge area long, with the sides extended into auriform 
processes; upper valve with a rounded and somewhat produced 
umbo, and concave near the margin; front or basal margin 
abruptly curved, deflected, and descending into a very broad 
space, which in depth is equal to the length of the shell; lower 
valve concave in the centre. Length of flat portion about 
three-quarters of an inch; width one inch and a half; deflection 
one inch. 
This species must not be confounded with L. analoya, to which it is 
very nearly allied. The outline of the latter approaches nearer to a 
semicircle, and it is usually larger than the L. depressa . 
Very common in the Amestry and Wenlock Limestones; 
and is also met with, although sparingly, in the Mountain 
Limestone. 
Its localities are Dudley, Wenlock; Amestry, May Hill; 
Abberley and Stourbridge. 
11. Lept.ena papilionacea. —The Butterfly-like Lep¬ 
tama, pi. LII. fig. 24. 
Spirifera papilionacea. Phillips, II. p. 221, pi. 11, fig. 6. 
Extremely wide, almost semielliptical; hinge line parallel; 
umbones very small; surface covered with very fine, longitudi¬ 
nal, bent, divergent stria); crenulated in the young state. 
Mountain Limestone, Bolland, Otterburn, and Kendal. 
MOLLUSCA. 
