AIR-BREATHERS OF THE COAL PERIOD. 167 



low 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. 



Explanation of Plate IV. 



Dendrerpeton Oweni i and Dermal Appendages. 



Fig. 1.— Skull. 



" 2. — Portion of mandible. 



" 3. — Maxillary bone, with outer teeth. 



" 4. — Teeth of same enlarged. 



" 5. — Maxillary bone, with inner teeth. 



" 6. — Tooth of same enlarged. 



" 7. — Intermaxillary. 



" 8. — Tooth of same enlarged. 



" 9 — Section of same enlarged. 



" 10 and 11.— Vertebrae. 



" 12 — [' rtion of pelvis. 



" 13. — iTiigments of ribs. 



" 14 — Ror.es of foot enlarged, (a) natural size. 



" 15. — ricapular bone, 



" 16. — Humerus. 



" 17. — Bones of hind leg. 



" 18 and 19. — Sculpturing of cranial bones, enlarged. 



" 20.— Bony scale. 



" 21. — Socket of inner tooth enlarged. 



" 22 and 25. — Integument of Dendrerpeton Oweni, with imbricated 



scales. 



" 23. — Integument of Hylonomus Lyelli. 



" 24, 26, 27, 28, 30.— Scales and appendages of the same enlarged. 



" 29. — Section of scale represented in Fig. 24. 



" 31. — Angular pendants or processes of H. Lyelli. 



" 32. — The same of H. aciedentatus. 



" 33 and 34. — Portions of the same enlarged. 



VII. Hylonomus Lyelli. 

 Plate V. 



In the original reptiliferous tree,discovered by Sir C. Lyell and the 

 writer, at the Joggine, in 1851, there were, beside the bones of 2?e»- 

 drerpeton Acadianum,some small elongated vertebrae, evidently of a 

 different species. These were first detected by Tro?. Wyman, ia 



