196 THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



neck or abdomen, or both. The use of these appendages is not easy to conjecture. They 

 remind us of the gular pouches of iguana, and of the lateral expansions of some geckos and 

 of the Draco volans. Possibly they formed lateral parachutes, aiding the animal in moving 

 over soft mud, or perhaps in leaping and swimming. 



"(6) Some other fragments appear to have belonged to a different species from either 

 of the foregoing. The best-preserved specimen, which is about i inch in length and half 

 an inch in breadth, is covered with very small imbricated scales. It is crossed by 6 or 7 

 obscure ridges, which both at the bottom and along a mesial line project into points 

 covered with larger scales. A row of large scales with round pores connects these along 

 the lower side. If, as seems probable, this fragment belonged to the side of the trunk or 

 tail, it would perhaps indicate a division of the subcutaneous muscles into an upper and 

 lower band, as in the newts. A separate fragment with transverse horny ridges and 

 another with a longer lobe, similar in structure to those above mentioned, may perhaps 

 be referred to the same animal. A larger patch of skin presents similar imbricated scales, 

 but without a mesial line, and with an edging of larger scales. 



' ' Six species of reptiles have left their bones in the repositories containing these 

 remnants of cuticle. Of these, Dendrerpeton acadianum, was an animal of too great size 

 to have been clothed with integument of this character and of such dimensions. Hylono- 

 mus aciedentatus and Hylerpeton dawsoni are each represented by only a single specimen, 

 and these did not occur in proximity to any of the portions of cuticle, except that the 

 appendages were found near a specimen of the former. Of the three remaining species, 

 Dendrerpeton oweni, from its size, the number of specimens found, and the juxtaposition 

 of their bones to the fragments of cuticle, appears to have the best claim to the integu- 

 ment included under Nos. i, 2, and 3; and in this case, while the creature had its throat, 

 and perhaps its abdomen, armed with bony scales, its upper parts and tail, as well as its 

 limbs, had a uniform covering of small, thin imbricated horny scales, in the manner of 

 many modern reptiles. 



" If the remaining portions of integument, Nos. 4 and 5, as would seem likely, belonged 

 to two species, both of smaller dimensions, there would seem little reason to doubt that 

 these were Hyionomus lyelli and H. ivymani. In this case, both of these species must have 

 possessed a highly ornate covering of horny scales and appendages, comparable with that 

 of many of the modern lizards, while there seems good reason to believe, as stated in a pre- 

 vious paper, that they were in part protected by bony scales somewhat like those of Den- 

 drerpeton. These points, however, we shall consider more in detail under the sections 

 which refer to the species of Hyionomus. 



" Before leaving these curious specimens of ancient skin, the most ancient I suppose 

 known to exist, it is of interest to observe that the thicker portions, when broken across, 

 have the aspect of jet, or of pure shining coal, and thin slices, under the microscope, have 

 the same rich brown colour with that material, though rather more translucent. When 

 burned, fragments of the substance give a strong flame, and a bituminous and ammoniacal 

 odour. We have thus an example of the production of coal from animal membrane, no 

 doubt gelatinous and horny in the first instance, but which has proved itself capable of 

 the same chemical changes that have been experienced by the vegetable matter buried 

 with it. In order that this substance should be preserved in this way, it would be neces- 

 sary that it should either be kept dry and hard, or that it should be immediately buried 

 in matter impervious to air and kept moist. The latter conditions are the more probable. 

 The preservative qualities of the peaty vegetable matter imbedded with it must be con- 

 sidered ; and it is possible that these hollow stumps, partly filled with fragments of Sigillaria 

 bark, may have formed natural tan-pits, in which animal membranes would be preserved 

 in a manner impossible in ordinary sediments. If this were the case, we may yet find an 

 entire reptile, preserved as a flattened mummy, in one of these strange repositories." 



