Lingula. 
MOLLUSCA. 
107 
Tlie Mountain Limestone, Northumberland. 
9. Lingula truncata. —The Truncated Lingula, pi. LIII. 
fig. 4. 
Lingula truncata. Sowerby, Geo. Trans. IV. 2nd series, p. 
339, pi. 14, fig. 15. 
Ovate, smooth, longitudinally compressed, most so in the 
centre of the valves; base parallel. 
Lower Greensand, Kent. 
10. Lingula cornea. —The Horny Lingula, pi. XLIX.* 
fig. 1. 
Lingula cornea . Murchison, Sil. Syst. p. 603, pi. 3, fig. 3. 
Oblong; umbonal region subacute, gradually widening to¬ 
wards the centre, from whence the sides are nearly parallel; 
base very slightly rounded, or nearly flat. 
Lowest beds of the Old Red Sandstone. 
11. Lingula minima. — The Very Small Lingula, pi. 
XLIX* fig. 2. 
Lingula minima . Murchison, Sil. Syst. p. 612, pi. 5, fig. 23. 
Oblong, somewhat elongated; beaks subacute ; flat, smooth, 
and thin, with parallel sides, a lit tie broader below than above; 
base but slightly rounded. Length four lines; width two lines 
and a half. 
Found in the Upper Ludlow Rock at Dovvton Castle and 
Delbury. 
12. Lingula lata. —The Broad Lingula, pi. XLIX.* fig. 3. 
Lingula lata. Murchison, Sil. Syst. p. 618, pi. 8, fig. 11. 
Obovate; beaks rather produced; flat, smooth; sides and base 
rather rounded. Length three lines; breadth about two lines. 
Lower Ludlow Rock, in escarpments, at Evenhay, Elton, &c. 
13. Lingula striata. —The Striated Lingula, pi. XLIX.* 
fig. 4. 
Lingula ? striata. Murchison, Sil. Syst. p. 619, pi. 8, fig. 12. 
Obovate, very much compressed, somewhat quadrangular; 
beaks but slightly developed ; base nearly parallel; whole sur¬ 
face with minute, transverse stria?. Length five lines; breadth 
four lines. 
Lower Ludlow Rock near Amestry. 
14. Lingula attenuata.— The Attenuated Lingula, pi. 
XLIX* fig. 5. 
Lingula attenuata. Murchison, p. 641, pi. 22, fig. 13. 
Elongated, compressed, smooth, acuminated above, wide be¬ 
low; beaks prominent and acute; sides rather fiat above, some¬ 
what rounded below ; and the base slightly arcuated. Length 
seven lines and a half; breadth five lines. 
Lower Silurian Rocks, Golden Grove, Caermarthenshire; 
Meadow Towm and Rorington, Salop. 
15. Lingula Lewisii, —Lewis’s Lingula, pi. XLIX* fig. 6. 
Lingula Lewisii. Murchison, p. 615 and 631, pi. 6, fig. 9. 
Oblong, compressed, smooth; beaks very obtuse; a little flat 
above, and somewhat produced below ; sides parallel. Length 
one inch and two lines; breadth nine lines and a half. 
Common in the Silurian Rocks, of which it is highly charac¬ 
teristic; the Amestry Limestone, Ludlow promontory; at Mary 
Knoll; Palmer’s Cairn; and Sunny Bank: it also occurs in the 
Wenlock Shale at Tynewydd, Wenlock, and Buildbwas. 
16. Lingula? truncata. —The Truncated Lingula, pi. 
XLIX * fig. 7. 
Lingula truncata . Sowerby, Geo. Trans. IV. 2nd series, p. 
339, ph 14, fig. 15. 
Ovate, compressed ; beaks hardly elevated above the body; 
sides nearly parallel; base straight. 
Lower Greensand, Kent. 
Genus II—CRANIA_ Iietzius. 
Shell inequivalve, suborbicular, mostly equilateral, 
slightly irregular; upper valve patelliform, very convex, 
interiorly provided with two projecting callosities, its 
umbo placed rather behind the centre; lower valve adhe¬ 
rent, nearly flat, pierced on its end or surface with three 
unequal or oblique holes; each valve with four muscular 
impressions; two of those in the upper valve are situate 
near the posterior margin, the other nearer the centre, 
but always close to each other; in the lower valve two 
are almost marginal, and remote, but the other two are 
nearly central, and so close together that they seem 
united, with usually a small projection between them; 
destitute of a hinge. 
1. Crania Parisiensis. —The Parisian Crania, pi. LIII. 
fig. 1, 2, 3, 4. 
Crania Parisiensis. De France, Diet, des Sci. Nat. La¬ 
marck, VI, pt. 1st, p. 259* Cuvier and Brongniarte, Geo. des 
Env. de Paris, Ed. 1822, p. 15, pi. 3, fig. 2. Sowerby, V. p. 3, 
pi. 408. Criopus Parisiensis , Fleming, p. 377. 
Suborbicular, compressed; upper valve thin, smooth in the 
centre, with obscure, granulated, irregular spines round the 
edges; its umbo small, acute, and placed a little to one side; 
margin folding over, and descending beyond the elevated edge 
of the lower valve; lower valve thick, with a considerably 
elevated margin, and cellular in its structure, a few nearly obso¬ 
lete, divergent stria? upon its inner surface, and attached by its 
whole outer surface; muscular impressions variable, sometimes 
exceedingly indistinct, and at others very deep; the elevation 
between the central ones also varies, being sometimes elevated 
along with it, in which case it has a strong resemblance to the 
human cranium. 
Found attached to fragments of the shells of Catillus } &c., in 
the Chalk, particularly that of Norfolk. 
Genus III_SPIRIFER— Soiverby. 
Shell transverse, equilateral, inequivalve; hinge 
straight, linear, widely extended equally on both sides 
of the umbones, which are more or less remote, being- 
separated by an intermediate flattened area, varying con¬ 
siderably in breadth in different species, and consists of 
three triangular parts, a central and two lateral ones; 
this area is divided in the centre by a triangular pit, for 
the passage of a byssus; within the smaller valve, and 
near the umbo, two spiral testaceous appendages are 
attached, whose convolutions diminish in size as they 
diverge from the centre of the shell. 
