102 



MOLLUSCA. 



PiLEOPSIS. 



1. Ancylus elegans. — The Elegant Ancyliis, pi. XLVII. 

 tig. 32 and 35. 



Ancylus elegans. Sowerby, VI. p. 64, pi. 533. Fleming, 

 p. 280. Brown, Elts. Foss. Conch, p. 64, pi. 4, fig. 14. 



Subconical, rather convex, smooth ; apex pointing obliquely 

 lo one side, and situate near the narrower end of the shell ; 

 aperture subovate, narrower at the apicial end, and more point- 

 ed, the o|)posite extremity rather flattened; surface covered 

 with extremely minute, divergent stria;, which are only disco- 

 verable by the aid of a strong lens. Height nearly equal to 

 half its greatest diameter. 



Dark-gray sand of the London Clay at Hordwell. 



Genus IV—CALYPTRJE A.— Lamarck. 



Shell conical ; vertex subcentral, imperforate, and 

 acute ; b;ise of aperture orbicular, or nearly so, its m.ir- 

 gins sharp and entire; internal cavity provided with a 

 lateral salient appendage, or septum, wliich varies much 

 in form in different species ; various species have a 

 strongly marked, muscular impression, just above the 

 fold of the inner lip ; in other species, it is situate on the 

 outside of the inner cup, but never within it. 



SECTION I. — TROCHIFORM, THE SEPTUM SOMEWHAT SPIRAL. 



1. Calvptb.ea echinulatum The Spined Calyptra;a, 



pi. XLVII. fig. 36, 37. 



Infundibulum echinulatum. Sowerby, I. p. 221, pi. 97. fig. 

 2. Fleming, p. 363. 



Smootn, conical, depressed, oblique, inflated on the sides ; 

 with three or four spiral convolutions, the apicial one acute, and 

 two or three lower ones smooth ; body with regular series of 

 rather obscure, short spines, which are most developed near the 

 edge. Diameter three-quarters of an inch. 



Plastic Clay at Plumstead. 



2. Calyptb^a RECTUM. — The Rectangular Calyptra>a, pi. 

 XLVII. fig. 38, 39. 



Infundibulum rectum. Sowerby, I. p. 220, pi. 97, fig. 3. 

 Fleming, p. 362. 



Conical; apex central; body inflated; spire with two or three 

 obsolete volutions, ending in an acute, nearly central vertex ; 

 aperture nearly circular; internal plate rectangular, and with 

 one volution; columella slender; external surface concentrically 

 striated. 



The Crag at Holywells. 



3. Calyptr^a obliquum. — The Oblique Calvptra^a, pi. 

 XLVII. fig. 40, 41, 42. 



Infundibulum obliquum. Sowerby, I. p. 220, pi. 97, fig. 1. 

 Fleming, p. 363. 



Subconic, somewhat depressed, very smooth, oblique; vertex 

 turned to one side; aperture circular; internal transverse parti- 

 tion reaching two-thirds across the inside, its edge reflected near 

 the columellar region, and having the aspect of an umbilicus. 

 Fig. 42, natural size of the shell. 



London Qay, Barton Cliff, and at Brakenhurst, Surrey. 



4. Calvptrjea spindlosum. — The Spinous Calyptra-a, pi. 

 XLVII. fig. 46, 47. 



Infundibulum sjjinuiosum. Sowerby, I. p. 222, pi. 97, fig. 

 6. Fleming, p. 363. 



Subconic, ventricose ; with three or four obscurely defined 

 volutions, the superior ones slightlv inflated ; vertex nearly 

 central, the apex acute ; surface covered with numerous, small, 

 extremely short, somewhat reflected hollow spines ; aperture 

 orbicular ; outer lip curved internally ; the transverse septum 

 reaching three-fourths across the cavity ; slightly twisted at the 

 base of the columella, producing the appearance of a subum- 

 bilicus. Diameter nearly an inch and a half. 



London Clay at Barton Clill'. 



5. Calyptb^a tuberculatum The Tuberculated Ca- 



lyptra>a, jil. XL\'II. fig. 45. 



Infundibuluvi tuberculatum. Sowerby, I. p. 221, pi. 97, fig. 

 4, 5. Fleming, p. 363. Ti'ochtts apertus, Brander, Foss. 

 IIant.pl. 1, fig. 1, 2. 



Subconic, inflated, oblique ; spire with two or three volu- 

 tions, apex obtuse ; whole surface covered with spiral bands of 

 rugose tubercles; aperture subrotnnd. 



London Clay, Hampshire. 



Genus V— PILEOPSIS.— Z,aj«arcA. 



Shell obliquely conical, posteriorly recurved, with an 

 uncinate spiral apex ; the volutions serrated, and rolled 

 inwards; aperture large, ovate; anterior margin shortest, 

 the posterior one large, and rounded; inside with two 

 elongated, arcuated, muscular impressions, situated under 

 the posterior margin ; external surface covered with a 

 thick, horny, somewhat pilous epidermis. 



1. PiLEOPSis unguis. — The Hoof Pileopsis, pi. XLVII. 

 fig. 43, 44. 



Patella unguis. Sowerby, II. p. 88,* pi. 139, fig. 7. Capu- 

 lus unguis, Fleming, p. 364. 



Subdepressed, suborbicular; vertex recurved, oblique, extend- 

 ing beyond the margin, the convolution small and acute ; base 

 suboval, contracting internally ; outer lip even. Height about 

 a third of its width. 



Found in the Crag at Holywells. 



2. PiLEOPSis stbiatus The Striated Pileopsis, pi. 



XLVII. fig. 49. 



Pileopsis striatus. Phillips, II. p. 224, pi. 14, fig. 15. 



Oval; apex placed near one end; vertex incurved, and free; 

 arcuated from the base to the vertex ; outer surface covered 

 with strong, sharp, radiating stria?, crossed by numerous, remote, 

 transverse lines of growth ; base suboval. 



Mountain Limestone, Northumberland, BoUand, and County 

 of KiUlarc, Ireland. 



3. Pileopsis Neritoides. — The Nerita-formed Pileopsis, 

 pi. XLVII. fig. 48 and 51. 



Pileopsis Nei-itoides. Phillips, II. p. 224, pi. 14, fig. 16, 

 17, 18. 



Obliquely spiral ; spire depressed, with two volutions, the 

 apex blunted ; aperture oval ; outer surface with strong, irregu- 

 lar lines of growth, and concentrically striate at the base. 



Mountain Limestone at Bolland. 



