Lign. 171. Archæoniscus Brodiei. Purbeck limestone. Vale of Wardour. (Drawn by S. P. Woodward, Esq.)
Impressions of the upper and under surfaces.
One species of fossil Isopod has been found in green fissile marl, at Montmartre; and another in fine-grained limestone, probably, from Pappenheim.[448] No fossil remains of this order had been noticed in the British strata, until the discovery of the Archæoniscus in the Purbeck strata by the Rev. P. B. Brodie. The quarry in which these relics were found is situated at Dallards, near the village of Dinton, about twelve miles west of Salisbury. They are principally distributed in a bed of light-brown and grey limestone, in the lower part of which are numerous fresh-water bivalves (cyclades), and a few small oysters. These Isopods often occur in clusters (see [Lign. 171]); the lenses of the compound eyes are sometimes detectable in the limestone, and, rarely, attached to the head; traces of legs have been observed, but no antennæ. In the same stratum the elytron (sheath, or wing-case) of a coleopterous insect was discovered. Mr. Brodie has obtained specimens an inch and a half in length, and an inch broad. These fossils appear to have been deposited tranquilly at the bottom of the water which they inhabited, since they are usually found imbedded with their legs downwards, and generally well preserved.[449]
[448] Nat. Hist. Crust. Foss. p. 138.
[449] See Brodie’s Fossil Insects, pp. 3 and 10.
The Archæonisci also occur in the Purbeck insectiferous limestone of Durlstone Bay, near Swanage, and have been discovered in strata of a similar character at the Ridgway railway-cutting between Dorchester and Weymouth, by the Rev. Osmond Fisher, of Dorchester.
Entomostraca.—The Crustaceans that we have above noticed belong to the Sub-class Malacostraca; and we have now to describe some fossil genera belonging to various divisions of the Entomostracous Crustaceans.
Lign. 172. Fossil. Limulus, in a Nodule of Ironstone: 1/2 nat.
Carb. Coalbrook Dale.