104 
MOLLUSCA. 
Patella. 
3. Emarginula sulcata —The Furrowed Emarginula, pi. 
XLVIII. fig. 16, 16,* 17. 
Emarginula scalaris. Sowerby, VI. pi. 519, fig. 4. 
Somewhat acutely conical, with the vertex slightly turned 
downwards; surface with about seventeen 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 Anclifle. 
This shell has been confounded with the preceding species, but will at 
once be distinguished by the ribs being more acute, and better defined. 
4. Emarginula tricarinata. —The Three-keeled Emar¬ 
ginula, pi. XLVIII. fig. 14, 14,* 15. 
Emarginula tricarinata. Sowerby, VI. p. 34, pi. 519, fig. 
2. Fleming, p. 366. 
Conical; the vertex considerably bent down, and rather acute 
at the apex; surface with three principal, much thicker, 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 Anclifle. 
5. Emarginula crassa. — The Thick Emarginula, pi. 
XLVIII. fig. 9, 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 III—PIIYLLIDIACEA. 
The branchiae of the animals situated beneath the 
margin ol the mantle, in a longitudinal series around the 
body. They respire in water. Shell simple. 
Genus IX.—PATELLA.— Linnccus. 
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 
lorm as the shell, placed about half way betwixt 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 the apex to the 
base, in the latter case, the 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 mucronate, central, and 
acute; aperture nearly orbicular, the marginal lips a little con¬ 
cave. 
Mountain Limestone, Bolland. 
2. Patella 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 age. 
London Clay at Stubbington. 
3. Patella rugosa —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 sinuosa —The Crooked Patella, pi. XLVIII. 
fig. 19* 
Patella sinuosa. Phillips, II. 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 scutiformis —The Scuttle-shaped Patella, 
pi. XLVIII. fig. 20. 
Patella scutiformis. Phillips, II. p. 223, pi. 14, fig. 1. 
Scutiform, smooth, elliptical, depressed; vertex indexed, 
acute, situate near the margin of the narrow end; surface with 
very fine, divergent striae. 
Mountain Limestone, Bolland. 
6. Patella lvevis. —The Smooth Patella, pi. XLVIII. 
fig. 21, 22. 
Patella Icevis. Sowerby, II. p. 86,* pi. 139> fig* 3, 4. Pa¬ 
tella Icevior , Fleming, p. 288. 
Subconic, slender, depressed; vertex obtuse, and eccentric; 
surface very smooth, and shining; aperture oviform. 
Alum Clay of Whitby and Folkstone. 
7. Patella lata* —The Broad Patella, pi. XLVIII. fig. 23. 
Patella lata. Sowerby, V. p. 133, pi. 484, fig. 2. Fleming, 
p. 288. 
