126 



MOLLUSCA. 



LePTjENA. 



striae, and longitudinal, scattered spines ; towards the sides and 

 basal margin a series of strong, irregular ribs, with a few blunted 

 and large spines ; margin much indented, and irregular. 

 Carboniferous Limestone, Kirby Lonsdale. 



45. LEPTa;NA FiMBRiATA — The Fringed Leptsena, pi. 

 LIV. fig. 8. 



Producta fimbriaia. Sowerby, Min. Conch. V. p. 85, pi. 

 459, fig. 1. Phillips, Geo. York. IL p. 215, pi. 8, fig. 11, 12. 



Oblong, nearly hemispherical ; umbo large, and produced ; 

 mesial furrow slight, or none; with from six to eight transverse, 

 crenated furrows, the ridges spinose on their superior margin ; 

 lesser valve concave, and similar to the large one. 



Carboniferous Limestone, Derbyshire ; BoUand ; Greenhow 

 Hill ; Moulton ; and Isle of Man. 



46. Lept-ena comoi'des. — The More-handsome Leptsena, 

 pi. LIII.* fig. 16. 



Productus como'ides. Sowerby, Min. Conch. IV. p. 31, pi. 

 329. Phillips, Geo. York. II. p. 213, pi. 7, fig. 4. 



Semicircular; globose near the beak; disk much inflated; 

 surface with fine, undulating stria;, and some large, shallow, lon- 

 gitudinal furrows ; hinge area flat ; substance of the shell very 

 thick, and rough within. 



Carboniferous Limestone, Llangaveni and Conishead, Wales; 

 and BoUand, Yorkshire. 



47. Lept^na membranacea The Membranous Lep- 



t£ena, pi. LIII.* fig. 17. 



Leptcena membranacea. Phillips, Pal. Fos. p. 60, pi. 25, 

 fig. 101. 



Semicircular, very flat, and thin ; hinge line parallel, extend- 

 ing the whole width of the shell, and produced, with spines ; 

 concentrically striated ; with undulating lines, among which are 

 some irregular, small spines. 



Phillips mentions two varieties, viz., a, pi. 25, fig. 101 a, with nume- 

 rous transverse lines; and b, fig. 101 i, with few transverse lines. 



Devonian Limestone, Pilton, North Devon ; and South 

 Petherwin, Cornwall. 



48. Lept^na aculeata The Spined Leptsena, pi. 



LIII.* fig. 36, 37. 



Productus aculeatus. Sowerby, Min. Conch. I. p. 156, pi. 

 68, fig. 4. Conchiliolithus (Anomites) acideatus, Martin, Pet. 

 Derb. pi. 37, fig. 9, 10. 



Orbicular ; hinge line half the breadth of the shell ; concave 

 valve smooth ; convex valve gibbous, with adpressed, reflected 

 spines, most numerous towards the sides, and a few obscure, 

 concentric undulations; base slightly indented. 



Carboniferous Limestone, Bakewell, Derbyshire. 



49. Lept^na longispina. — The Long-spined Leptsena, 

 pi. LIV. fig. 62, 63. 



Productus longispinus. Sowerby, Min. Conch. I. p. 154, pi. 

 68, fig. 1. Productus Flemingii, lb. p. 155, pi. 68, fig. 2. 



Semicircular, broader than long ; hinge line extending the 

 whole width of the valves, and prolonged into large, auricular 

 processes, somewhat blunted at their termination; convex valve 

 with a mesial furrow ; smaller valve concave ; one very long, 

 round, tubular, horizontal spine, and several smaller ones, placed 

 near each side in the convex valve. 



Carboniferous Limestone, Kilbride, Lanarkshire; and Moun- 

 tain Limestone, Linlithgowshire, Scotland ; and North Sunder- 

 land. 



50. LEPT.SNA sarcinulata. — The Little-truss Leptsena, 

 pi. LIII.* fig. 40. 



Leptsena sarcinulata. Sowerby, Sil. Syst. p. 610, pi. 3, fig. 

 10 b and 12 c, and pi. 5, fig. 13. Ure's Rutherglen, p. 317, pi. 

 16, fig. 10, 11. 



Semicircular; hinge line parallel; provided with eight or ten 

 long, divaricating, simple, tubular spines; upper valve convex, 

 somewhat depressed in the middle ; lower valve concave ; sur- 

 face covered with numerous, very fine, radiating ribs. Length 

 about half its breadth. 



This is one of the most characteristic species of the Upper Ludlow 

 Limestone. 



Lower Silurian Limestone, Horderley; Cardoc, Bala, Conis- 

 ton, Felindre, Horeb Chapel, &c. 



51. Lept^na latissima. — The Very-broad Leptsena, pi. 

 LIIL* fig. 38. 



Productus latissimus. Sowerby, Min. Conch. IV. p. 32, pi. 

 330. Phillips, Geo. York. IL p. 214, pi. 8, fig. 1. 



Much elongated transversely, fusiform, or convoluted ; hinge 

 line whole width of valves, and partially concealed by the beak; 

 umbo much incurved ; entire surface with coarse, longitudinal 

 strisB, and many small, bristle-like spines. 



This has somewhat the appearance of X. como'ides, but is much shorter 

 than that species, with the cardinal area considerably narrower. 



Carboniferous Limestone, Kirby Lonsdale ; Fountains' Fell ; 

 Otterburn, Northumberland; Anglesea, Wales; and the Island 

 of Arran, Frith of Clyde, Scotland. 



52. LEPT.SNA coNVOLUTA. — The Convoluted Leptsena, 

 pi. LIII.* fig. 39. 



Leptcena convoluta. Phillips, Pal. Fos. p. 57, pi. 24, fig. 

 96. 



Somewhat semicircular ; hinge line the whole width of the 

 valves, and extended into rounded, auriform processes ; middle 

 of lower valve regularly convex, with a depression between it 

 and the auricles ; surface with fine, rounded, numerous, longi- 

 tudinal, divergent striae. 



Devonian Limestone, Croyde Bay, North Devon. 



53. LEPTaiNA GiGANTEA. — The Gigantic Leptjena, pi. 

 LV.fig. 12. 



Productus giganteus. Sowerby, Min. Conch. IV. p. 19, pi. 

 320. Phillips, Geo. York. IL p. 215, pi. 8, fig. 5, reduced. 



Transversely elongated, much inflated ; hinge line nearly 

 parallel, and extended into auriform processes ; surface with 

 irregular, undulating, radiating, obtuse ribs, covered with waved, 

 unequal strife. 



This species attains the size of nine inches in diameter. 



Carboniferous Limestone of Derbyshire; Hawes; Dent Dale; 

 Northumberland ; and Fifeshire. 



54. Lept^na punctata. — The Punctured Lepta;na, pi. 

 LV. fig. 20, 21, 22, and 24. 



Productus punctatus. Sowerby, Min. Conch. IV. p. 22, pi. 

 323. Phillips, Geo. York. II. p. 215, pi. 8, fig. 10. Anomites 

 jmnctatus, Martin, Pet. Derb. pi. 37, fig. 6, 7, 8. 



Obovate ; hinge line about a third less than the width of the 

 shell ; larger valve gibbose, with a deep mesial furrow ; surface 

 with concentric, wide, imbricated, laminar ridges, and furrows ; 

 and numerous, minute, short spines ; lesser valve nearly flat, 

 with shallow concentric furrows, and flattened ridges. 



Mountain Limestone, Derbyshire; BoUand; Settle; Buxton; 

 Otterburn ; and Cork, Ireland. 



