EXPLANATION OF PLATE 27. 43 



Fig. 8. a. Tube on the under surface of a scale for the 

 passage of the mucous duct. See V. I. Note, p. 

 191, 192. (Agassiz.) 

 Fig. 9. Anterior extremity of the lower jaw of Holop- 

 tychus Hibberti, from the Lime stone of Burdie 

 h^use, near Edinburgh. See Note, V. I. p. 275. 

 The rugged surface of this bone is very remarkable. 

 (Hibbert.) 

 Fig. 9'. Small teeth of Holoptychus Hibberti, fluted 

 externally towards their base, and having a hollow 

 cone within. (Hibbert.) 

 Fig. 9'". A small tooth magnified. (Hibbert.) 

 Fig. 10. One of the larger teeth in the Jaw of Holop- 

 tychus Hibberti, deeply fluted at the base, and hav- 

 ing a hollow cone within. None of these teeth have 

 sockets, but they adhere by a bony attachment to 

 the jaw. (Hibbert.) 

 Fig. 11. Tooth of Holoptychus Hibberti. (Hibbert.) 

 Fig. 12. Tooth of Megalichthys Hibberti.* (Hibbert.) 

 Figs. 13, 14. Teeth of Holoptychus Hibberti. (Hib- 

 bert.) 

 Figs. 11. 12. 13. 14. are from Burdie house. 



* Since the discovery of Megalichthys, which we have quoted in 

 V. I. p. 276, Mr. W. Anstice, of Madeley, has found two jaws and 

 punctate scales of the same species, in nodules of Iron stone from 

 the Coal field of Coalbrook Dale ; he has also found Ichthyodoru- 

 lites, bones of fishes, and Coprolites, forming the nuclei of other 

 balls of the same Iron stone. 



Mr. Murchison has still more recently (1835) discovered remains 

 of the Megalichthys, Holoptychus, and Coprolites, with several 

 species of Unio, in the Wolverhampton Coal field. These great 

 Sauroid fishes, which were first recognized at Edinburgh, in Sept. 

 1834, have also been detected in the English Coal fields of New- 

 castle on Tyne, Leeds, and Newcastle under Lyne. 



