648 
DR. J. W. DAWS OR OR ERECT TREES CORTAIRIRG ARIMAL 
black at their distal edges, and their pores appear as round transparent spots ; viewed 
as an opaque object, the scaly skin appears black and shining, and the edges of 
the scales seem to be very thin and to bend upward as if free from the skin. 
The bristle-like appendages of Hylonomus are also translucent, when mounted in 
balsam; but even under a high power show only a faint indication of longitudinal 
fibrous structure (see woodcut, figs. 1 to 5). The thicker plates, when sliced, show, 
near the base, a few curved canals, probably vascular, but the upper part appears quite 
compact, and under a high power merely shows faint indications of tortuous fibres or 
tubes. Even the thickest show no bony structures whatever^ and have throughout 
a carbonaceous or bituminous appearance. 
When burned, the cuticle and horny scales give a strong flame, and emit a bitu¬ 
minous and ammoniacal odour, their chemical characters being those of highly 
bituminous coal or jet. 
These portions of cuticle and horny scales are of rare occurrence, and appear to have 
owed their preservation to being embedded in wet fragments of bark and other 
vegetable matter, perhaps possessing a tanning quality; small loose bodies of similar 
character have been found which may have been horny plates detached from the skin 
by decay, but it is impossible to say to what they belonged. One of these is a 
semi-circular plate, about half an inch in diameter, and studded with conical tubercles. 
It may have been the armature of the snout of one of the Micfosauria . 
For additional descriptions and illustrations, see ‘Air-breathers of the Coal Period/ 
p. 34, and Plates 1, 4 and 5 ; and ‘Acadian Geology/ pp. 369-373. 
Scales and Appendages op Hylonomus and Dendrerpeton. 
Eig. 1. Ornamental horny processes of Hylonomus Lyelli, x 10. 
,, 2. Horny tubercles of the same, X 10. 
,, 3. Cuticle and scales of Dendrerpeton (transparent), X 10. 
,, 4. The same (opaque), x 10. 
,, 5. Portion of the same, X 50, showing cutaneous pore at (a). 
