MOSASAURUS. 63 
described. It also bears a near resemblance to a specimen described by Prof. F. 
Emmons,' under the name of Elliptonodon compressus. 
The enamelled crown is an inch and a half long, and is elliptical in transverse 
section, as represented in the accompanying outlines, No. 19, representing sections 
below the middle and at the base. The latter measures an inch 
antero-posteriorly, and ten lines transversely. ‘The acute ridges Syarte 
divide the crown into two surfaces about equal in extent and con- 
vexity. The surfaces exhibit a faint disposition to subdivide 
towards the base, but for four-fifths of their length are smooth. 
The transverse annulation, represented by the artist in the figure, 
is only one of staining of the enamel, though there is a feeble 
constriction of the crown corresponding with the band above its middle. The base 
of the specimen is excavated in a funnel-shaped manner from a thin sharp edge at 
the periphery to the central pulp cavity. 
18. Two specimens of teeth, from Mount Holly, Burlington County, New J ersey, 
contained in the museum of the Academy of Natural Sciences. 
One of the specimens, represented in Fig. 9, Plate LX, consists of the shed crown 
of a tooth, much worn at the apex. In its present condition it measures nineteen 
lines long, extending from the enamel border at the base, and in transverse section 
is elliptical, as represented in the outer of the accompanying outlines, No. 20. The 
antero-posterior diameter at base, in the perfect condition, measured sixteen lines, 
and the transverse diameter is thirteen lines and a half. The surfaces, about 
equally divided by the anterior and posterior acute ridges, are entirely devoid of 
subdivisional planes. The enamel is more rugose than in any of the preceding 
teeth, but otherwise I can see no important difference between it and several of 
those last described. ‘The base is excavated in a salver-form manner, from a broken 
edge about a line in thickness, to the central pulp cavity. 
The second specimen, represented in Fig. 10, Plate IX, Apa 
consists of a comparatively small tooth, with the apex of the 
crown broken off so as to expose the summit of the pulp cavity. 
In color and general character the specimen looks as if it may 
have belonged to another part of the dental series of the same 
individual as its larger companion. 
In form the crown has nearly resembled that of the specimen described as No. 
12, represented in Fig. 4, Plate IX. When perfect it has measured about thirteen 
lines long; and its circular base is eight lines in diameter. It is irregularly divided 
by the acute ridges, of which the anterior is almost entirely obliterated by wear. 
The inner surface is much more extensive than the outer, and both are smooth, 
presenting neither trace of subdivisional planes nor rugosities. The inner curve of 
the base is fifteen lines and a half, the outer curve eleven lines. The inner of the 
accompanying outlines, No. 20, is a transverse section from the base of the crown. 
The straight fusiform fang is two inches and a quarter long, and appears as if it 
had not been coossified with its alveolus. Just back of the centre of the inner side 
* North Carolina Geological Survey, 222, figs. 41, 42. 
