Atrypa. 
MOLLUSCA. 
127 
55. Lept^na ovalis —The Oval Leptsena, pi. LV. 
fig. 23. 
Producla ovalis. Phillips, Goo. York. p. 216, pi. 8, fig. 14. 
Oblong; hinge line slightly arcuated; larger valve very gib- 
bose; umbo very large, and much produced; mesial furrow 
slight, with nearly obsolete, concentric furrows; provided with 
numerous, spinulose puncta; lesser valve very flat, with a few 
slight, concentric furrows. 
Mountain Limestone, Bolland. 
56. Leptjena hemisphjerica —The Hemispherical Lep¬ 
tsena, pi. LV.* fig. 16. 
Producta hemisphcerica. Sowcrby, Min. Conch. VI. p. 117, 
pi. 561. 
Orbicular; larger valve inflated, with numerous, fine, longi¬ 
tudinal, irregular strife, and wide, concentric, slightly developed 
ridges; hinge line parallel, occupying about two-thirds of the 
width of the shell; lesser valve flat, and longitudinally striated. 
This species has been found five inches in diameter. 
Carboniferous Limestone, Coalbrook Dale. 
57* Leptn.ea interrupta.— The Interrupted-strife Lep- 
taena, pi. LIII.* fig. 34. 
Leptcena interrupta. Sowerby, Geo. Trans. V. 2nd series, 
pi. 56, fig. 7. 
Semicircular, very gibbose; hinge line about equal to the 
width of the shell; umbo but little produced; larger valve with 
longitudinal strife, interrupted by concentric ribs. 
Nearly allied to L. punctata. 
Devonian Limestone, Petherwin and Plymouth. 
58. Leptvena lobata. — The Lobed Leptcena, pi. LIII.* 
fig. 41,42. 
Productus lobatus. Sow'erby, Min. Conch. IV. p. 16, pi. 
318, fig. 1 to 6. Phillips, Geo. York. II. p. 214, pi. 8, fig. 7. 
Oblong, gibbose; beak much incurved; larger valve divided 
into two lobes, by the deep and wide mesial furrow; surface 
with numerous, deep, longitudinal, coarse, spinous striae. 
Distinguished from L . concinna , by the more deep mesial furrow and 
coarser striae. 
Carboniferous Limestone, Derbyshire; Clifton; the Island of 
Arran, Frith of Clyde; and Cork. 
59. Leptjena IIardrensis. —The Ilardren’s Leptcena, pi. 
LIII* fig. 32, 33. 
Orthis IIardrensis. Phillips, Pal. Fos. p. 138, pi. 58, fig. 
104, a, by c y d, and pi. 60, fig. 104.* 
Semicircular, almost twice as wide as long; hinge line straight, 
spinous, with acute and spined terminations; smaller valve a 
little concave; surface with numerous, very fine, radiating strife, 
minutely crossed by lines of growth; internal surface minutely 
punctated, with cordiform, muscular depressions. 
Devonian Limestone, Westieigh, North Devon. 
60. Lept.ena anomala. —The Anomalous Leptcena, pi. 
LIV. fig. 10, 11, and pi. LXVII. fig. 12. 
Leptcena anonuda. Sowerby, Min. Conch. VII. p. 9, pi. 
615, fig. 1. Pinna injlata, Phillips, Geo. York. II. p. 211, pi. 
6, fig. 1. Mylilus striatusy Fischer, Orgolit. Most*, p. 181, pi. 
19, fig. 4. 
Elongated, irregularly triangular; hinge area long, large, tri¬ 
angular, and acute; beak much produced, with spinose sides; 
compressed, and longitudinally striated. 
This species is generally very irregular, and distorted; the spines near 
the hinge arc small. 
Mountain Limestone, Bolland. 
61. Leptjena calva —The Smooth Leptcena, pi. LV. 
fig. 13, 14. 
Producta calva. Sowerby, Min. Conch. VI. p. 115. Pro - 
ductus horridus , lb. IV. p. 17, fig. 1. 
Subquadrangular; hinge line nearly parallel, with a row of 
spines on each side; beak large, much incurved; larger valve 
greatly inflated, with a deep and wide mesial furrow; surface 
smooth, with nearly equidistant, slightly marked lines of growth; 
lesser valve smooth, a little raised in the centre, with transverse 
lines of growth. 
Magnesian Limestone, Humbleton; Derbyshire; Midde¬ 
ridge ; and Glueksbrunn, Ireland. 
62. Leptjena humerosus— The Shouldered Leptsena, pi. 
LIII* fig. 43. 
Productus humerosus. Sowerby, Min. Conch. IV. p. 21, 
pi. 322. 
Oblong, somewhat square, compressed; hinge line not equal 
to the width of the valves; larger valve with two deep cavities 
near the beak, and a third connected with the beak; smaller 
valve rather flat; surface with fine, longitudinal strife. 
Carboniferous Limestone, Breden, near Derby; and York¬ 
shire. 
63. Leptjena personata. —The Masque Leptama, pi. 
LIII* fig. 44. 
Productus personatus. Sowerby, Min. Conch. IV. p. 20, 
pi. 321. 
Hemispherical; hinge line arcuated ; larger valve with three 
deep cavities, one connected with the beak, and two others 
remote ; surface smooth, irregularly striated longitudinally. 
Carboniferous Limestone, Derbyshire. 
64. Leptcena decepta. —The Deceptions Leptcena, pi. 
LIII* fig. 26. 
Leptcena sericea , var. Sowerby, Sil. Syst. pi. 19, fig* 2. 
Subtriangular; hinge line parallel, extending into auriform 
processes; base rather pointed; surface with remote, nearly 
equidistant, divergent, narrow ribs. 
Lower Silurian Bocks at Ccfn, Rhyddan, and Llandovery, 
Wales. 
Genus X ATRYPA— Konig. 
Shell longitudinal, equivalve, equilateral; hinge line 
slightly curved; umbones small, and not incurved. 
This genus is distinguished from its congeners by its 
short hinge line, and in being destitute of a large area, 
and also in having no foramen, or only a small triangular 
one. The shells are rounded, and without furrows; they 
have acute beaks, without a perforation. 
1. Atrypa didyma— The Spread Atrypa, pi. LIII.* fig. 
45, 46. 
Atrypa didyma. Dal man, Act. Holm. 1827, p. 146, pi. 6, 
fig. 7* Hi si tiger, Pet. Suec. p. 77, pi. 22, fig. 7* Sowerby, Sil. 
Syst. p. 610 and 614, pi. 6, fig. 4. 
Nearly globular; umbones small; base emarginatc; each 
valve provided with a central furrow, emanating from a little 
way below the beaks, and terminating at the base. Length 
and breadth five lines. 
