1;J0 REFEKENCES TO THE PLATES. 



Fig. 5. Tooth, tlie fang broken off, from Monmouth County, New Jersey. Pcstero-lateral view. 

 a, Inner, and b, outer surface of the crown, both of which are smooth. 



Fig. 6. Mutilated shed crown of a tooth from Burlington County, New Jersey. Inner view. Be- 

 sides exhibiting the divisional planes it is unusually striated. 



Figs. T-10. Teeth of Mosasaurus, from Monmouth County, New Jersey, from the same individual. 



Fig. 7. Internal view. The summit of the crown worn off; the fang coossified with the alveolus. 

 a, Exserted portion of fang ; b, inserted portion, coossiCed with its alveolus ; c, cavity for a succes- 

 sional tooth hollowed iu the fang. 



Fig. 8. Internal view of another tooth. The summit of the crown more worn than in the preced- 

 ing. References the same as in last figure. 



Fig. 9. Outer surface of the crown of the same tooth. 



Fig. 10. Internal view of another tooth. The fang presents two excavations for successional 

 teeth, a, lC.\.scrted portion of fang; h, inserted portion, coossified with its alveolus; c, d, cavities 

 for successional teeth ; e, the pulp cavity exposed. 



Fig. 11. Internal view of the crown of a tooth, broken from the fang, from Monmouth County, 

 New Jersey. Both sides of the crown are totally devoid of subdivisional planes. 



Fig. 12. Shed crown of a tooth, from St. George's, New Castle County, Delaware. External view. 



Fig. 13. Inner view of a specimen similar to the last, from Gloucester County, New Jersey. 



Figs. U, 15. Two teeth, from Freehold, Monmouth County, New Jersey, belonging to Dr. C. 

 Thompson. 



Fig. 14. Outer view of one specimen. 



Fig. 15. Inner view of the second specimen, a, Exserted portion of fang; b, inserted portion; 

 c, cavity for a successor. 



Fig. 16. Tooth, from Mullica Hill, Gloucester County, New Jersey. Outer view. The fang has 

 been broken oil'. 



Fig. 17. Crown of a tooth, from a Cretaceous formation of Alabama. Lateral view. The specimen 

 belongs to Dr. R. W. Gibbes, and is figured (llosasauriis and the allied Genera. Smiths. Cont. 

 PI. Ill, Figs. 6-9) by hira as characteristic oi Holcodiis acuiidens. The outer (a) and inner surfaces 

 (6), separated by acute ridges in front and behind, are subdivided into planes, which are somewhat- 

 depressed and striated. 



Fig. 18. Crown of a tooth, from a Cretaceous deposit, marked No. 4, in the section of Dr. Hay- 

 den, at the mouth of While River, Nebraska. Lateral view. It resembles the tooth represented in 

 the preceding figure, but is without the subdivisional planes, a, Section of the crown in outline; 

 h, section at the base of the crown. 



Fig. 19. Specimen, from the same locality as the preceding, retaining a portion of the crown and 

 fang, a, Section at the broken surface of the crown ; b, section at the base of the crown 



PLATE XI. 



All the figures, representing fragments of jaws and teeth of Mosasauruii, are of the natural size, 

 excepting Fig. 13, wlii.ch is one-half the diameter of the original. 



Figs. 1-4. Fragments, from Holmdale, Monmouth County, New Jersey, belonging to Prof Reiley, 

 of Rutgers College. 



Figs. 1, 2. Portions of the right pterygoid bone, a, b, r, Remains of the first, second, and third 

 teeth ; d, the fourth tooth ; e, f, the seventh and eighth teeth. 



Fig. 3. Posterior fragment of the right dental bone, containing an entire penultimate tooth. In 

 the specimen the fang of the tooth is visible through tho large foramen beneath, but has been inad- 

 vertently left out by the artist. 



Fig. 4. Fragment of the left side of the lower jaw, inner view, containing the antepenultimate 

 tooth entire, a, Cavity for a successional tooth ; b, exserted portion of the fang of the tooth iu 

 advance, the crown having been broken off; c, its successor exposed by the destruction of the inner 

 wall of the cavity containing it; d, minute successor included within the former, and accidentally 



