56 MOSASAURUS. 
Jersey, belonging to the museum of the Academy of Natural Sciences. It is 
represented in Fig. 3, Plate X, and was previously indicated and figured by Harlan’ 
and Morton.” In form it resembles the corresponding portion of the teeth above 
described, but is slightly larger. Its dividing ridges are distinctly denticulated; the 
outer surface is divided towards the base of the crown into four planes, which 
diminish and finally disappear towards the apex; the inner surface is divided into 
eleven planes, which also diminish and become obsolete towards the apex. The 
length of the crown when perfect has been about two inches and three-quarters ; 
the antero-posterior diameter at base about thirteen lines; and 
the transverse diameter is fourteen lines and a half. 
The base of the specimen is excavated in a trumpet-like 
manner, extending to a thin edge at the periphery of the 
crown. ‘This condition evidently indicates the specimen to 
have been shed during the life of the animal, notwithstanding 
the little wearing to which the tooth appears to have been 
subjected. 
The accompanying outlines, No. 3, represent sections from the base, middle, and 
near the apex of the specimen. 
6. The shed crown of a tooth, from Burlington County, iNew Jersey, presented 
to the Academy of Natural Sciences by Mr. L. T. Germain. ‘The specimen, repre- 
sented in Fig. 6, Plate X, has the apex and base broken, but when perfect appears 
to have been less than two inches and a half long, about thirteen lines in diameter 
antero-posteriorly and twelve lines transversely. The ridges of the crown are 
distinctly denticulated, but separate the surfaces less unequally than in the preceding 
specimens, The outer surface is subdivided into nine planes, passing into seven 
and then becoming obsolete towards the apex of the crown. The 
inner surface is subdivided into about twenty planes, diminishing 
and finally disappearing towards the apex of the tooth. The sub- 
divisional planes are more or less obscured. by longitudinal striation 
of the enamel, more especially on the inner side. This striation 
diminishes and finally disappears towards the apex. It does not 
exist in the specimens previously described. 
The accompanying outline, No. 4, represents a transverse section of the crown 
below its middle. 
‘The base of the specimen is excavated towards the central pulp cavity in a salver- 
form manner from a broken edge at the periphery about a line and a half thick. 
7. An entire tooth, from Monmouth County, New Jersey, loaned to me for exami- 
nation, from the collection of Rutger’s College, by Prof. Cook. The specimen 
represented in Fig. 3, Plate IX, I suspect to belong to the forepart of the lower 
jaw of Mosasauwrus. It is smaller, but has the same general form as the entire teeth 
previously described. 
The crown is more curved than in any of the preceding specimens, but like them 
No. 3. 
No. 4. 
* Journ. Acad. Nat. Sci., Vol. IV, Plate XIV, Figs. 2, 3, 4; Med. and Physical Researches. 
? Synopsis of Organic Remains, &c., Plate XI, Fig. 9. 
