174 AIR-BREATHERS OF THE COAL PERIOD. 



both batrachian and lacertian, in so far as our experience of modern 

 animals is concerned. It would however accord with observed 

 facts in relation to other groups of extinct animals, that the primi- 

 tive batrachians of the coal period should embrace in their struc- 

 tures, points in after times restricted to the true reptiles. On the 

 other hand, it would equally accord with such facts that the first- 

 born of lacertians should lean toward a lower type, by which they 

 may have been preceded. My present impression is, that they 

 may constitute a separate family or order, to which I would give 

 the name of Microsauria, and which may be regarded as allied, on 

 the one hand, to certain of the humbler lizards, as the Gecko or 

 Agama, and, on the other, to the tailed batrachians. 



It is likely that Hylonomus Lyelli was less aquatic in its habits 

 than Dendrerpeton. Its food consisted, apparently, of insects and 

 similar creatures. The teeth would indicate this, and near its bones 

 there are portions of coprolite, containing remains of insects and 

 myriapods. It probably occasionally fell a prey to Dmdrerpeton, 

 as bones, which may have belonged either to young individuals of 

 this species or to its smaller congener H. Wymani, are found in lar- 

 ger coprolites, which may be referredjvith probability to Dendrer- 

 peton Acadianum. 



Explanation of Plate V. 

 Hylonomus Lyelli, and Dermal appendages. 



Fig. 1. — Remains of a skeleton of a large individual of Hylonomus Lyelli; 



(a) Maxillary; (b) Mandible; (c) Ribs; (d) Vertebrae; 



(e) Humerus; (/) Femur; (g) Tibia; (h) Fibula, (£) 



Pelvis ; (k) Foot. 

 " 2.— Right Mandible. 

 " 3. — Maxillary. 



" 4, 5. — Portions of Maxillary, magnified. 

 « 6.— Extremity of Mandible, magnified. 

 " 7. — Sections of teeth ; (a) magnified, (6) highly magnified. 

 " 8. — Portion of cranium, magnified ; (a) natural size, (b) transverse 



section. 

 " 9. — Skeleton of the trunk of a small individual of H. Lyelli; (a) 



Fore limb, (b) Hind limb, (c) Ribs. 

 " 10. — Ribs from the slab, Fig. 1, magnified. 

 " 11. — Fore foot, magnified ; (a) natural size. 

 " 12. — Cross section of flattened femur, magnified. 

 •" 13, 14.— Portions of the bone of the same, more highly magnified. 



