178 THE GEOLOGIST. 



insects, &c. They will probably be rewarded by finding some wing- 

 cases of Orthopterous tribes, and it will be their first discovery in 

 Britain. 



Arachnicla (that is, spiders and scorpions) were probably not rare 

 in the coal-period. A fossil scorpion was found at Prague ; and 

 unless I am very much mistaken, I have seen relics of more than one 

 large spider from Coalbrooke Dale, in Shropsliire, 



In those celebrated trees described by Professor Dawson and Sir 

 Charles Lyell,* and which were found in the sandstone of ]N"ova Scotia, 

 millepedes (Xylobiits), or at all events some members of the myriapod 

 group, were found. They were associated, in the same hollow stumps, 

 with numerous small land-snails. These were somewhat like the 

 little Pupa, or chrysalis snail, so common on moss-grown 

 trees, in the deep woods of Old England. But I shall 

 never believe that coal-forests were like the woods of our 

 own times, for reasons which will immediately appear. 



One word, though, about the other land animals found 

 in these trees, for Prof. Dawson in his last communication 

 Fig. i.— to the Geological Society, f makes it extremely probable that 

 Pupavetusta. ^ QTQ were i an( j lizards to feed on and restrain this 

 insect-life within due bounds. They may have been amphi- 

 bious lizards — the larger species (JDendrerpeton AcaJiartv.m), found in 

 the coal-measures, certainly was so — yet the nature of the teeth of 

 another (the Hylonomus) , and its scaly armour, look too much like 

 those of living land lizards, to allow us readily to believe that it too 

 was a Batrachian reptile, modified for and adapted to this sort of life. 

 We must wait for more complete information. 



And now, with all these proofs that the creatures of the land lived 

 and died in the old coal-forests, why should we refuse to believe that 

 these grew upon dry land ? 



That dry land was not far off, I must, of course, admit. The muddy 

 sediment and sand that form the mass of the coal-measures were 

 derived from land ; and must have been formed, as sand and mud are 

 now formed, by the washing away of rock and earth — the daily 

 action of the tides and rivers. 



But the question is, whether the plants grew on the land, and were 

 then submerged ; or whether they grew in the water, and so were 

 mixed with the " spoils of animals, savage and tame," that lived in 

 the water. 



The commonest fossil in the coal measures — the one which par 

 excellence, is "the coal fossil" — is the Anthracosia, or Unio, as it used 

 to be called. 



This is a bivalve shell with closed valves, looking not at all 

 unlike the common Unios of our streams, but never showing any of 

 those peculiar wrinkles about the beak, which living Unios always 

 exhibit. 



* Quart, Joiuti. Geol. Society, vol. ix., p. 58. 

 f Ibid. vol. xvi, p. 275. 



