104 



MOLLUSCA. 



Patella. 



3. Emaroini'la sulcata. — Tlie Furrowed Emarginula, pi. 

 XLVin. fig. \G, \G,* 17. 



Emarginula acalaris. Sowerby, VI. pi. 519, fig. 4. 



Soiiiowhat acutely conical, with the vertex slightly turned 

 downwards; surface witii about scveutccn rather flat ribs, 

 which hardly protrude beyond the margin, the central one cleft 

 by the fissure, with broad furrows between each, which are 

 crossed by fine, somewhat irregular, nearly obsolete stria?; mar- 

 ginal fissure very short; aperture suborbicular. Fig. 16,* the 

 natural size. 



Found in the Oolite at Ancliffe. 



Tlii» shell has been confounded with the preceding species, but will at 

 once be llistingui^hed by the ribs being more acute, and better defined. 



4. Emabginl'la tricarinata. — The Three-keeled Emar- 

 ginula, pi. XLVIII. fig. 14, 14,* 15. 



Emargimila h-icarinata. Sowerby, VI. p. 34, pi. 519, fig. 

 2. Fleming, p. 3G6. 



Conical; the vertex considerably bent down, and rather acute 

 at the apex ; surface with three principal, much tliickcr, more 

 prominent, and widely-set divergent ribs, situated in front, the 

 central one cleft by the fissure, which is gradually closed as the 

 shell increases in size, and leaves a longitudinal, transversely 

 striate space in the centre of it, and about ten or twelve lesser 

 ribs on the sides and back, the intervening furrows almost 

 smooth ; aperture elongated, and slightly quadrangular. Fig. 

 14,* the natural size of the shell. 



Found in the Oolite at Ancliflfe. 



5. Emarginula crassa The Thick Emarginula, pi. 



XLVIII. fig. 1), 10. 



Emarginula crassa. Sowerby, I. p. 73, pi. 33, two upper 

 figures. Fleming, p. 365. 



Obtusely conical, very thick; vertex short, turned backwards, 

 and subacute at the apex; whole surface with nearly equidis- 

 tant, divergent, flat ribs, the intervening furrows with four or 

 five longitudinal stria; between each, crossed by many lines of 

 growth, which in old shells become very close and irregular 

 towards the base ; marginal fissure wide, and filled up half its 

 length by thinner shelly matter than the other parts ; aperture 

 oblong-oval, glossy within, margin somewhat undulated. 



The Crag near Ipswich. 



FAMILY IIL—PHYLLIDIACEA. 



The branchiae of tlic animals situated beneath the 

 margin of tlie mantle, in a longitudinal series around the 

 body. They respire in water. Slull simple. 



Genus IX — PATELLA Linmrus. 



Shell ovate or oblong, more or less of a conical form, 

 sometimes, although rarely, pyramidal ; vertex rarely 

 central, generally placed anteriorly, with its apex inclined 

 towards the head of the animal ; concave within, and the 

 margin entire ; muscular impressions distinct, and same 

 form as the shell, placed about half way betwLxt the 

 summit and the margin, interrupted in front, where the 

 head of the animal is situated ; external surface striated 



or ribbed in a variable manner, from tlie apex to the 

 base, in the latter case, tiie margin is variously dentated 

 or crenulated. 



1. Patella mucronata The Pointed Patella, pi. 



XLVIII. fig. 11. 



Patella mucronata. Phillips, II. p. 223, pi. 14, fig. 3. 



Smooth, subconic, depressed; apex niucronate, central, and 

 acute ; aperture nearly orbicular, the marginal lips a little con- 

 cave. 



Mountain Limestone, Bolland. 



2. Patklla striata — The Striated Patella, pi. XLVIII. 

 fig. 12, 13. 



Patella striata. Sowerby, IV. p. 123, pi. 389. Fleming, 

 p. 288. 



Oblong-ovate, slightly oblique, irregularly conical ; with nu- 

 merous, acute, irregularly large and small divergent ribs, here 

 and there interrupted by somewhat irregular lines of growth ; 

 sides frequently pressed inwards ; vertex acute, and placed 

 towards the anterior end ; inside thickened towards the apicial 

 region. 



Young shells are nearly flat, and acquire the conical form as they ad- 

 vance in nge. 



London Clay at Stubbington. 



3. Patella bugosa. — The Rugged Patella, pi. XLVIII. 

 fig. 18. 



Patella rugosa. Sowerby, II. p. 87,* pi. 139, fig. 6. Par- 

 kinson, III. p. 50, pi. 5, fig. 21. Fleming, p. 288. 



Obovate, thick, depressed ; apex placed near one end, de- 

 pressed, and slightly recurved ; dorsal end somewhat concave ; 

 surface with numerous, rather regular, divergent ribs, and with 

 two or three large reflected concentric undulations, which are 

 so much developed behind the vertex, that they give the 

 appearance of having been rolled together, and provided with 

 indistinct lines of growth. 



The Lower Oolite, Gloucestershire. 



4. Patella si.nuosa. — The Crooked Patella, pi. XLVIII. 



fig. 19. 



Patella sinuosa. Phillips, IL p. 223, pi. 14, fig. 2. 



Oviform, smooth, depressed, subconic ; vertex irregular, pro- 

 minent, and situate near the narrow end ; surface with indistinct 

 lines of growth. 



Mountain Limestone, Bolland. 



5. Patella scutieormis Tiic Scuttle-shaped Patella, 



pi. XLVIII. fig. 20. 



Patella scutif'urinis. Phillips, II. p. 223, pi. 14, fig. 1. 



Scutiform, smooth, elliptical, depressed ; vertex inflexod, 

 acute, situate near the margin of the narrow end ; surface with 

 very fine, divergent stria;. 



Mountain Limestone, Bolland. 



6. Patella l^evis. — The Smooth Patella, pi. XL\III. 

 fig. 21,22. 



Patella Levis. Sowerby, IL p. 86,» pi. 139, fig. 3, 4. Pa- 

 tella Itcviur, I'leming, p. 288. 



Subconic, slender, depressed ; vertex obtuse, and eccentric ; 

 surface very smooth, and shining; aperture oviform. 



Alum Clay of Wiiitby and Foikstone. 



7. Patella lata.— The Broad Patella, pi. XLVIII. fig. 23. 

 Patella lata. Sowerby, V. p. 133, i)l. 484, fig. 2. Fleming, 



p. 288. 



