2?6 THE OLDEST AIR-BREATHERS 



footprints referred to previously belong to this animal, it 

 must have frequented the shores, either in search of garbage, 

 or on its way to and from the waters. The occurrence of its 

 remains in the stumps of Sigillaria, with land snails and milli- 

 pedes, shows also that it crept in the shade of the woods in 

 search of food ; and in noticing coprolitic matter, in a subse- 

 quent page, I shall show that remains of excrementitious 

 substances, probably of this species, contain fragments attri- 

 butable to smaller reptiles, and other animals of the land. 



All the bones of Dendrerpeton hitherto found, as well as 

 those of the smaller reptilian species hereafter described, have 

 been obtained from the interior of erect Sigillariae, and all of 

 these in one of the many beds, which, at the Joggins, contain 

 such remains. The thick cellular inner bark of Sigillaria was 

 very perishable ; the slender woody axis was somewhat more 

 durable ; but near the surface of the stem, in large trunks, 

 there was a layer of elongated cells, or bast tissue, of consider- 

 able durability, and the outer bark was exceedingly dense and 

 indestructible. l Hence an erect tree, partly imbedded in 

 sediment, and subjected to the influence of the weather, be- 

 came a hollow shell of bark ; in the bottom of which lay the 

 decaying remains of the woody axis, and shreds of the fibrous 

 bark. In ordinary circumstances such hollow stems would be 

 almost immediately filled with silt and sand, deposited in the 

 numerous inundations and subsidences of the coal swamps. 

 Where, however, they remained open for a considerable time, 

 they would constitute a series of pitfalls, into which animals 

 walking on the surface might be precipitated ; and being prob- 

 ably often partly covered by remains of prostrate trunks, or 

 by vegetation growing around their mouths, they would be 

 places of retreat and abode for land snails and such creatures. 

 When the surface was again inundated or submerged, all such 



1 See a paper by the author, on the Structures of Coal, Journal of the 

 Geological Society, vol. xv. ; also " Supplement to Acadian Geology." 



