Atrypa. 



MOLLUSCA. 



127 



55. Lept^ena ovalis. — The Oval Lepta?na, pi. LV. 

 fig. 23. 



Producta ovalis. Phillips, Geo. 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 fmrows ; provided with 

 numerous, spinulosc puncta; lesser valve very flat, witii a few 

 slight, concentric furrows. 



Mountain Limestone, BoIIaml. 



50. Lept^na HEMisPH.uiucA. — The Hemispherical Lep- 

 t£Bna, pi. LV.* fig. 16. 



Producta hemisphwrica. Sowerby, Min. Conch. VL p. 117, 

 pi. 561. 



Orbicular ; larger valve inflated, with numerous, fine, longi- 

 tudinal, irregular stria;, and wide, concentric, slightly developed 

 ridges; hinge line parallel, occupying about two-thirds of the 

 width of tiie 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-striae Lep- 

 tsna, pi. LIIL* fig. 34. 



LeptcBna 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 strise, interrupted by concentric ribs. 



Nearly allied to L. punctata. 



Devonian Limestone, Petherwin and Plymouth. 



58. LEPT.ENA LOBATA. — The Lobed Lepta^na, pi. LIIL* 

 fig. 41,42. 



Productus lobatus. Sowerby, Rlin. Concli. IV. p. 16, pi. 

 318, fig. 1 to 6. Phillips, Geo. York. IL 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 stria?. 



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. Lept.ena Hardrensis The Hardren's Leptaena, pi. 



LIIL* fig. 32, 33. 



Orthis Hardrensis. Phillips, Pal. Fos. p. 138, pi. 58, fig. 

 104, a, h, c, 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 viith numerous, very fine, radiating stria;, 

 minutely crossed by lines of growth ; internal surface minutely 

 punctated, with cordiform, muscular depressions. 



Devonian Limestone, Westleigh, North Devon. 



60. Lept.ena anomala The Anomalous Leptaina, pi. 



LIV. fig. 10, 1 1, and pi. LXVII. fig. 12. 



Lepttena anomala. Sowerby, Min. Conch. VII. p. 9> pi- 

 615, fig. 1. Pinna injlata, Phillips, Geo. York. II. p. 211, pi. 

 6, fig. 1. Mylilus striatus, Fischer, Orgoht. Mosc. 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 are small. 



Mountain Limestone, Bolland. 



61. LepTjENA calva. — The Smooth Leptacna, pi. LV. 

 fig. 13, 14. 



Producta calva. Sowerby, Min. Conch. VI. p. 115. Pro- 

 ductus horridus, lb. IV. p. 1 7, fig. 1 • 



Subquadraugular ; 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 Glucksbrunn, Ireland. 



62. Lept^ena humerosus. — The Shouldered Leptana, pi. 

 LIIL* 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 striae. 



Carboniferous Limestone, Breden, near Derby ; and York- 

 shire. 



63. Lept^na personata. — The Masque Leptacna, pi. 

 LIIL* 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. Lept^ena decepta. — The Deceptions Leptaena, pi. 

 LIIL* fig. 26. 



Leptcena sericea, var. Sowerby, Sil. Syst. pi. 19, fig. -■ 

 Subtriangular ; hinge line parallel, extending into auriform 



processes ; base rather pointed ; surface with remote, nearly 



equidistant, divergent, narrow ribs. 



Lower Silurian Rocks at Cefn, Rhyddan, and Llandovery, 



Wales. 



Genus X ATRYPA — Kiinig. 



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. LIIL* fig. 



45, 46. 



Atrypa didyma. Dalman, Act. Holm. 1827, p. 146, pi. 6, 

 fig. 7. Hisinger, Pet. Suoc. p. 77, pi. 22, fig. 7. Sowerby, Sil. 

 Syst. p. 610 and 614, pi. 6, fig. 4. 



Nearly globular ; umbones small ; base emarginate ; 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. 



