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EXPLANATION OF PLATES 27d.
Fig. 1. Psammodus, from Mountain limestone, Bristol.
Fig. 2. Orodus, from the same.
Fig. 3. Acrodus, from the Lias, Lyme Regis.
Fig. 4. Ptychodus, (upper surface) from the Chalk.
Fig. 5. Side View of fig. 4.
Figs. 6—10. Teeth of extinct fossil Sharks in the subfamily of Hybodonts; in this family the enamel is plicated on both sides of the teeth. See V. I. p. 219, Note.
Fig. 6. Side view of tooth of Onchus, from the Lias at Lyme Regis.
Fig. 7. Front view of the same.
Figs. 8. 9. 10. Teeth of Hybodonts, from the Oolitic slate of Stonesfield, Oxon.
Figs. 11. 12. 13. Fossil Teeth of true Sharks in the Squaloid division of that family, having the Enamel smooth on the outer side. From the Chalk and London clay. See V. I. p. 220, Note.
Fig. 14. Palatal teeth of Myliobates striatus, from the London clay of Barton cliff, Hants. See V. I. p. 221. Much of the enamel is worn away by use, as frequently happens in the tongue and palatal bones of living Rays. (Original.)
C. Petrified remains of an extinct Genus of Shark.
Fig. 1. Jaw of Hybodus reticulatus, from the Lias at Lyme Regis, (scale one half.) Many of the Teeth retain their place on the margin of the bone. The granulated structure of bone is distinctly preserved. (De la Beche.)
Fig. 2. Teeth selected from the Jaw last figured. Nat. size.
Fig. 3. Ichthyodorulite, from the Lias at Lyme Regis, being the Dorsal spine of Hybodus incurvus, set with teeth-like hooks, to suspend the membrane of the dorsal fin. (De la Beche.)
