300 
SILUEIA. 
[Chap. XII. 
right in the woodcut represents the large shell, Productus hemisphgericus, which 
in nature is four inches broad, and shows by comparison the very great size of 
the Coral, which has a width of two feet five inches *. 
Of all its fossils, however, the large Producti are the most characteristic of 
the great limestone group, the same species being found in this rock through 
many degrees of latitude in Europe, Asia, and America, and even in India and 
Australia. 
Besides these numerous evidences of the presence of the sea, Unio-like shells 
(Anthracosiae), probably of estuarine habitats, every now and then occur in thick 
layers as we ascend in the series, and are among the most characteristic of the 
upper portions of the formation. 
An estuarine intermixture is observable in coal-bearing strata of parts of Shrop- 
shire, Staffordshire, Lancashire, and elsewhere. It is well seen in the district 
Fossils (80). Insect and Shells op the Coal-measures. 
1. Wing of Cory- 
dalis ? Brongni- 
arti, Mantell. 
2. Productus sca- 
briculus, Sowerby. 
3. Anthracosia 
acuta, Sow., sp. 
(Formerly sup- 
posed to be allied 
to Unio. Silur. 
Syst. p. 105.) 
of Coalbrook Dale, where remains of Insects (allied to the Corydalis of Ame- 
rica) are found associated with Marine and Estuarine Shells and Land Plants. 
The figures in Foss. 80 represent this case of intermixture as formerly pointed 
Fossils (81). Fern from the Coal of Coalbrook Dale. 
Pecopteris loncbitidis, Sternberg. (From Sil. Syst. p. 105.) 
out by myself. A fuller account, however, is given of it by Mr. Prestwich, in 
his elaborate memoir on the strata and fossils of that district f . 
* See Silurian System, p. 107. This Coral is 
from Lilleshall, Shropshire, where the limestone 
rises out from beneath the coal. 
t Trans. G-eol. Soc. Loncl., 2nd ser., vol. v. p. 413. 
One of the Plants, Pecopteris lonchitidis, which is 
given in the woodcut, Foss. 81, is associated in 
these tracts with forty or fifty species of terrestrial 
Plants belonging to Calamitacese, Polypodiacc se, 
and Lycopodlacese. Of these, Stigmaria ficoides 
(root of Sigillaria), Neuropteris cordata, Odon- 
topteris obtusa, and the Pecopteris here figured 
are perhaps the most common. 
