EXPLANATION OF PLATE XXXIV. 



All the figures two-thirds the size of nature except Figs. 12-22, which are of the natural 

 size. 



Figs. 1 to 5 and 10. Clidastes intermedials. From the Cretaceous of Alabama, Museum of the Acad- 

 emy of Natural Sciences. 



Fig. 1. Outer view of the fore part of the left mandible. 



Fig. 2. Back part of the right mandible, outer view reversed. 



Fig. 4. Reserve tooth, concealed in the excavated base of the last of the series in the speci- 

 men of Fig. 1, seen from within. 



Fig. 5. Reserve tooth, concealed in the excavated base of the second of the series of the same 

 specimen, seen from within. 



Figs. 6 to 9 and 11. Clidastes affinis. From the Smoky Hill River, of Kansas. Belonging to the mu- 

 seum of the Smithsonian Institution. 

 Fig. 6. Outer view of the left inaudible. 



Fig. 7. Inner view of back part of the right mandible, exhibiting the glenoid articulation. 

 Fig. 8. Upper view of two fragments of the cranium. 

 Fig. 9. The basi-sphenoid bone. 



Fig. 10. C. Ixteiimedius. The axis seen below and with the fore part downward. 



Fig. 11. C. affixis. The left humerus, posterior view. 



Fig. 12. Lestosaurus coryphaeus: 



Greater portion of a palate-bone, with teeth, natural size. From the Smoky Hill River, 

 Kansas. 



Fig. 13. Clidastes affixis. Tooth contained within a jaw-fragment. From Smoky Hill River, Kansas. 



Fig. 14. Crown of a similar tootli. From L'Eau qui Court County, Nebraska. It is compressed, conical, 

 curved, with acute borders and smooth surfaces. Fig. 15. Section of the same tooth. 



Figs. 16-22. Teeth of mosasauroids, natural size, together with the preceding specimen from L'Eau qui 

 Court County, Nebraska. Presented to Swarthmoro College by George S. Truman. 



Fig. 16. Crown of a shed tooth, with striated enamel. Fig. 17. Transverse section of the 

 same, at the base. 



Fig. 18. Shed crown of a large tooth, with striated enamel, anterior view. 



Fig. 19. Shed crown of a tooth, with distinct subdivisional planes. .Fig. 20. Outlines of sec- 

 tions of the same at the base and above the base. 



Fig. 21. Crown of another shed tooth, intermediate in character with the two preceding. 

 Fig. 22. Outline of a section of the same at the base. 



