REFERENCES TO THE PLATES. 129 



Pig. 2. Antero-internal view of an anterior tooth, from Moumoutli County, New Jersey. a, 

 External surface of crown ; h, internal surface ; c, fang. 



Fig. 3. Antero-internal view of an anterior tooth, from Monmouth County, New Jersey, belonging 

 to Rutgers College, a, External surface of crown ; &, internal surface ; c, fang. 



Fig. 4. Inner view of an anterior tooth, from Monmouth County, New Jersey, a. Inner surface 

 of the crown ; h, impression of cavity for a successional tooth. 



Fig. 5. Small fragment of a jaw, with a tooth and portion of another, inner view, from Monmouth 

 County, New Jersey, a, Internal surface of the crown exhibiting the divisional planes ; h, portion 

 of crown of the adjoining tooth ; c, exserted portion of fang ; d, portion of fang within alveoli and 

 coossilied therewith ; e, three large cavities for successional teeth ; /, communication of the latter 

 cavities with the pulp cavities of the teeth in use. 



Fig. 6. Tooth, with small attached portions of the jaw, found with that of Fig. 5, and from the 

 same individual. Internal view, a, Inner surface of crown ; 6, exserted portion of fang ; c, portion 

 of fang coossified witu the interior of the alveolus ; d, fragment of outer part of the jaw ; e, large 

 cavity, apparently for a pair of successional teeth ; /, large pulp cavity. 



Fig. 7. Tooth, internal view, from Monmouth County, New Jersey, a, The inner surface of the 

 crown, which is devoid of divisional planes ; h, fang without trace of coossific attachment. 



Fig. 8. Inner view of the crown of a shed tooth, from Monmouth County, New Jersey, belonging 

 to Dr. C. Thompson. It resembles the corresponding part of a Crocodile tooth more than the 

 ordinary forms of the Ifosasaurus teeth. 



Figs. 9, 10. Two teeth, internal view, from Mount Holly, Burlington County, New Jersey. From 

 the color and structural appearance the two teeth look as if they had been derived from tlie same 

 individual. The crowns bear a close resemblance to the corresponding part of the teeth of the 

 Crocodile, a. Impress upon the postero-internal surface of the fang of a cavity for a successional 

 tooth. The specimen, represented by Fig. 9, is a shed crown, as proved by the excavated appearance 

 of the base. 



Fig. 11. Shed crown of a tooth, from St. George's, New Castle County, Delaware. Internal view. 

 It strongly resembles a Crocodile tooth. 



Figs. 12, 13. Tooth of Polygonodon vetus, from Burlington County, New Jersey, from the coUec- 

 tion of Prof. Cook. 



Fig. 12. Posterior view. 

 I Fig. 13. External view. 



PLATE X. 



All the figures, representing teeth of Mosasaurus, are of the natural size. 



Fig. 1. Tooth, from Freehold, Monmouth County, New Jersey, belonging to Dr. C. Thompson. 

 Inner view, a, The crown exhibiting divisional planes of the inner surface well-marked ; b, the 

 osseous fang, longitudinally furrowed, and exhibiting no trace of former attachment with the sides 

 of the socket in which it was inserted ; c, impression of a cavity originally occupied by a successor 

 to the tooth placed in advance ; d, deeper cavity for a successional tooth. 



Fig. 2. Tooth, from Monmouth County, belonging to Rutgers College. Outer view. The crown 

 exhibiting one of the acute ridges which separate the outer surface a, from the inner surface b ; both 

 the latter present well-marked divisional planes ; c, the fang, which was coossified with its alveolus, 

 a fragment of the jaw being seen at d. 



Fig. 3. The shed crown of a tooth, from near Woodbury, Gloucester County, New Jersey. Lateral 

 view, a, Outer ; 6, inner surface, separated by a sub-denticulated ridge, and both presenting divi- 

 sional planes. 



Fig. 4. Tooth, from Monmouth County, New Jersey, from the same individual as those represented 

 in Figs. 7-10, and Figs. 5, 6, Plate IX. Internal view, a, Inner surface of the crown, which has 

 but one carina ; 6, exserted portion of fang ; c, bottom of fang, which was coossified with its alveolus ; 

 d, large cavity for a successional tooth. 



17 May, 1865. 



