Family—Palaeophonidae, Palaeophonus (figs. 48 and 49).
Sub-order Dionychopoda.—The 3rd, 4th, 5th and 6th pairs of appendages slender, not evenly tapering, the segments longer than wide; the apical segment short, distally truncate, and provided with a pair of movable claws. Basal segments of the 5th and 6th pairs of appendages abutting against the sternum of the prosoma (see fig. 10 and figs. 51, 52 and 53).
Family—Pandinidae (Pandinus, Opisthophthalmus, Urodacus).
” Vejovidae (Vaejovis, Jurus, Euscorpius, Broteas).
” Bothriuridae (Bothriurus, Cercophonius).
” Buthidae (Buthus, Centrums).
” *Cyclophthalmidae (Cydophthalmus) Carboniferous.
” *Eoscorpiidae (Eoscorpius, Centromachus) Carboniferous.
 | Fig. 49.—Ventral view ofa restoration of PalaeophonusHunteri, Pocock, the Silurianscorpion from Lesmahagow,Scotland. Restored by R.I.Pocock. The meeting of thecoxae of all the prosomaticlimbs in front of the pentagonalsternum; the space fora genital operculum; the pairof pectens, and the absenceof any evidence of pulmonarystigmata are noticeable in thisspecimen. |
| (See Pocock, Quart Jour. Micr.Sci., 1901.) |
Remarks on the Order Scorpiones.—The Scorpion is one of the great animals of ancient lore and tradition. It and the crab are the only two invertebrates which had impressed the minds of early men sufficiently to be raised to the dignity of astronomical representation. It is all the more remarkable that the scorpion proves to be the oldest animal form of high elaboration which has persisted to the present day. In the Upper Silurian two specimens of a scorpion have been found (figs. 48, 49), one in Gothland and one in Scotland, which would be recognized at once as true scorpions by a child or a savage. The Silurian scorpion Palaeophonus, differs, so far as obvious points are concerned, from a modern scorpion only in the thickness of its legs and in their terminating in strong spike-like joints, instead of being slight and provided with a pair of terminal claws. The legs of the modern scorpion (fig. 10; fig. 51) are those of a terrestrial Arthropod, such as a beetle; whilst those of the Silurian scorpion are the legs of an aquatic Arthropod, such as a crab or lobster. It is probable that the Silurian scorpion was an aquatic animal, and that its respiratory lamellae were still projecting from the surface of the body to serve as branchiae. No trace of “stigmata,” the orifices of the lung-chambers of modern scorpions, can be found in the Scottish specimen of Palaeophonus, which presents the ventral surface of the animal to view. On the other hand, no trace of respiratory appendages excepting the pectens can be detected in the specimen (see fig. 49).