AMPLEXUS, CEPHALOPODA. al 
Ure, in his History of Rutherglen and Kilbride, says, ‘‘it (the former) is 
sometimes found enclosed in Ironstone like a nucleus; at other times, found 
among shells, along with marine shells, &c. —specimens are very rare.” It 
has also been met with in the Transition Limestone of Gloucestershire, and 
in the lowest bed of Limestone, near the Hotwells, Bristol. 
Genus XVIII. — BELEMNITES. — Lamarck. 
Generic Character. — Shell straight, conical, consisting of 
two parts ; external portion or sheath forming a thick solid 
shield, provided with a cavity at the base, to admit the 
alveole, which is more mathematically conical than the 
sheath; and is separated into chambers by smooth simple 
septa, which are perforated by a lateral siphon. 
Belemnites abbreviatus. Plate II. tigs. 41, 42. 
The Belemnites are only known in a fossil state. They have received many 
vulgar appellations, such as petrified fingers, petrified arrows, thunder stones, 
spectre candles, and devils’ fingers, &c. 
Genus XIX. — ORTHOCERA., — Lamarck. 
Generic Character. — Shell elongated, straight, or slightly 
arcuated, with numerous external longitudinal grooves or 
ribs ; chambers separated by transverse septa, these are per- 
forated by a tube, which is either central or marginal. 
Orthocera simplex. Plate II. tig. 29. 
Sowerby has united this genus with the following, under the name of 
Nodosaria. 
Genus XX. — NODOSARIA. — Lamarck. 
Generic Character. — Shell elongated, erect, or smooth, 
and slightly arcuated, sub-conic, nodose, consisting of a 
series of spherical volutions ; transverse septa perforated. 
Nodosaria ——— Plate | fig. 
Genus XXI. — PHRAGMOCERAS, — Broderip. 
Generic Character. — Shell incurved and compressed, 
more or less conical ; septa entire at their edges, crossed 
externally by the lines of growth ; siphuncle placed near the 
inner margin; aperture contracted at the middle, its outer 
extremity produced into a sub-cylindrical beak. 
Phragmoceras ventricosum. Plate VIL. fig. 5. 
This genus is distinguished from Orthocera, by the shells being curved, and 
by the siphuncle being nearly marginal. The species are known only in a 
fossil state, and are characteristic of the Silurian system of rocks. 
Genus XXII. — AMPLEXUS. — Sowerby. 
Generic Character. — Shell cylindrical, multilocular, 
