88 



MOLLUSCA. 



28. P. BiSERRATA The Doubly-serrated Pleurotomaria, 



pi. XL. fig. 35. 



Pleurotomaria hiservata. Phillips, Geo. of Yorkshire, II. 



p. 228, pi. 15, fig. 29. 



Shell acutely conical ; body not quite so long as the spire ; 

 suture of the spire, and lower angle of the volutions, provided 

 with a doubly serrated carina, and between them a crenulated 

 line; base provided with three concentric furrows; and the 

 whole surface obliquely striate. 



Found in the Mountain Limestone, Derbyshire. 



29. P. TORNATiLis. — The Turned Pleurotomaria, pi. XL. 



fig. 36. 



Pleurotomaria tornatilis. Phillips, Geo. of Yorkshire, II. 



p. 228, pi. 15, fig. 25. 



Shell ovate ; body large, inflated ; spire small, consisting of 

 four ventricose volutions ; base somewhat pointed, and acute ; 

 body invested by a very broad, spiral, mesial band, with a fur- 

 row on each side, continued around the base of the volutions 

 of the spire ; base provided with two concentric furrows ; the 

 whole surface covered with distinct, spiral stria?. 



Found in the Mountain Limestone, Bolland. 



30. P. SQUAMULA The Scaly Pleurotomaria, pi. XL. 



fig. 37. 



Pleurotomaria squamula. Phillips, Geo. of Yorkshire, II. 

 p. 227, pi. 15, fig. 17. 



Shell regularly conical ; body and spire of nearly equal 

 length ; sides almost flat ; spire consisting of five volutions ; 

 whole surface covered with numerous, squamous, oblique ribs, 

 either entire or bifurcate, or alternately long and short. 



Found in the Mountain Limestone, Bolland. 



31. P. ciRRiFORMis The Cirrus-shaped Pleurotomaria, 



pi. XL. fig. 38 and 42. 



Helix? cirriformis. Sowerby, Min. Conch. II. p. I6O, pi. 

 171, fig. 2. 



Shell conical, ventricose ; volutions a little tabulate above ; 

 aperture nearly circular ; a broad, raised, mesial band traverses 

 the centre of the body and volutions of the spire, and is crossed 

 by arcuated stria; ; whole surface covered with longitudinal and 

 spiral, distinct, small, arcuated strise ; base with a narrow um- 

 bilicus. 



Found in the Mountain Limestone of Derbyshire. 



32. P. EXCAVATA The Excavated Pleurotomaria, pi. XL. 



fig. 39. _ 



Pleurotomaria excavata. Phillips, Geo. of Yorkshire, II. 

 p. 228, pi. 15, fig. 20. 



Shell conical; the volutions tumid, and provided with a sharp 

 carina on their sides; almost plain above and below ; umbilicus 

 closed. 



Found in the Mountain Limestone at Bolland. 



33. P. FusiFORMis. — The Spindle-shaped Pleurotomaria, 

 pi. XL. fig. 40. 



Pleurotomaria fit^iformis. Phillips, Geo. of Yorkshire, II. 

 p. 227, pi. 15, fig. 16. 



Shell smooth, fusiform ; spire not quite so long as the body ; 

 sides of the volutions rather flat, and furnished with three spiral 

 carina:;, the lower one sutural ; aperture ovate. 



Found in the Mountain Limestone, Bolland. 



34. P. SERRILIMBA — The Tooth-bordered Pleurotomaria, 

 pi. XL. fig. 41. 



Natica. 

 Phillips, Geo. of Yorkshire, II. 



Pleurotomaria serrilimba. 

 p. 228. 



Shell acutely conical; body very short; spire long, with nearly 

 flat sides ; the band which traverses the lower margin, with a 

 serrated margin. 



Found in the Mountain Limestone, Derbyshire. 



35. P. COMPRESSA. — The Compressed Pleurotomaria, pi. 

 XXXIIL* fig. 16, 17. 



Helicina compressa. Sowerby, Min. Conch. II. p. 33, pi. 

 10, three middle figures. 



Shell thick, strong, depressed ; body large ; spire short, con- 

 sisting of three nearly flat-sided volutions; aperture subovate, a 

 little angular above ; body provided with an elevated, sharp, 

 narrow, mesial band, which also invests the lower part of the 

 volutions of the spire. 



Found in the Mountain Limestone of Leicestershire. 



Genus XLII.— SIGARETUS.— Z.a?««rc;j. 



Shell subauriform, somewhat orbicular, and depressed, 

 generally with a nearly marginal, hardly prominent spire, 

 consisting of two or three volutions; aperture entire, 

 longer than wide, greatly dilated, with its edges disunited 

 at the upper extremity, and embracing the lower part of 

 the body ; inner lip short, spirally twisted, and for the 

 most part a very little reflected above, but in some in- 

 stances so much so, as to form a small umbilicus ; inside 

 of the aperture exhibiting two muscular impressions, one 

 at the upper, and the other at the lower extremity. 



1. S. CANALicuLATUS The Canaled Sigaretus, pi. XLIII. 



fig. 16, 17. 



Sigaretus canaliculatus. Sowerby, Min. Conch. IV. p. 1 15, 

 pi. 384. 



Shell slightly ovate, convex; spire depressed, with two canali- 

 culate volutions, terminating in a pointed apex ; aperture sub- 

 ovate, rounded below, and somewhat square next the columella, 

 over which the inner lip is broadly reflected, with a large 

 umbilicus behind; whole surface covered by longitudinal stria?, 

 which are decussated by transverse lines of growth. Length 

 varying from half an inch to three-quarters. 



Found in the London Clay at Hordwell. 



FAMILY V._NERITACEA. 



Shells inhabiting the sea and fresh waters; semi- 

 globular, or oval in their form ; destitute of a columella ; 

 the margin of the inner lip sharp edged, and placed 

 transversely; always provided with an operculum. 



Genus XLIII.— NATICA Adanson. 



Shell subglobose, oval, or oblong ; umbilicate ; spire 

 short, sometimes very short, with apex very rarely 

 pointed; aperture large, semicircular, and very seldom 



