58 MOSASAURUS. 
no trace of a cavity for a successor, and the entrance to its pulp cavity is like that 
in the preceding specimen. 
10. A mutilated tooth, from Burlington County, New Jersey, presented to the 
Academy of Natural Sciences by Charles C. Abbott. It is intermediate in form 
and size with the specimens numbered 7 and 8. ‘The outer surface of the crown, 
corresponding with the antero-posterior diameter, is eight lines and a half, and it 
exhibits three planes. The inner surface exhibits eight planes, and the transverse 
diameter equals the former one. The accompanying outline, No. 8, represents a 
section near the base of the crown. ‘The fang is curved cylindroid, slightly com- 
pressed, and measures two inches and a quarter in length. Its ner side posteriorly 
exhibits a small lenticular excavation, three lines long, produced by a successional 
tooth. 
11. Two teeth, which have lost their fangs, from Monmouth County, New Jersey, 
presented to the Academy of Natural Sciences by E. D, Cope. The specimens, 
represented in Fig. 5, Plate X, and Fig. 12, Plate XI, look as if they had béen 
derived from the same individual. They correspond in form with the more familiar 
one viewed as characteristic of Mosasaurus, but they are smooth or 
devoid of subdivisional planes, or at most exhibit only the feeblest 
disposition to their development at the base of the crown. The 
pulp cavity, within the specimens, presents the outward form of 
the crown. The length of the more perfect specimen, Fig. 5, from 
the enamel border of the base of the crown to the worn apex, is 
twenty-two lines; its antero-posterior diameter at base is eleven 
lines; its transverse diameter the same. The accompanying outlines, No. 9, repre- 
sent transverse sections near the base of the crown, and just below and above the 
middle. The length of the crown of the other specimen, Fig. 12, is two inches. 
12. An entire tooth, from Monmouth County, New Jersey, presented to the 
Academy of Natural Sciences by Dr. J. H. Slack. It is represented in Fig. 4, Plate 
IX, and is intermediate in size with those of the approximate Figs. 
- 2 and 3, to which it also bears a general resemblance in form. 
The unworm crown is twenty lines long, and is nearly circular in 
transverse section, as represented in the accompanying outlines, 
No. 10, taken from the base and below the middle. The diameter 
of the base of the crown antero-posteriorly is ten lines and a half; 
the transverse diameter nine lines and a half. The ridges separating 
the surfaces of the crown are minutely denticulated, and both surfaces are smooth 
or entirely devoid of subdivisional planes and striations. The inner surface is a 
little more extensive than the outer one, as represented in the accompanying 
sections. 
The fang is straight, cylindroid, and measures two inches and a half in length 
and thirteen lines in diameter. It exhibits no evidence of having been coossified 
with its alveolus, and on the inner side posteriorly, as represented in Fig. 4, 6, it 
presents a small excavation for the accommodation of a successional tooth. At the 
free extremity it presents a funnel-shaped pit, prolonged into the central canal of 
communication with the pulp cavity. 
No. 9. 
No. 10. 
