AND GREAT LIGNITE FORMATIONS OF NEBRASKA. 
141 
sess knowledge. The character which renders them unique, is the wearing away of the 
crown transversely, as in the herbivorous quadrupeds.” 
Subsequent researches of Dr. Mantell led to the conclusion that the Iguanodon was a 
huge herbivorous saurian, which masticated its food in the manner of the existing pachy¬ 
derm mammals. 
Among the most interesting palaeontological discoveries of Dr. Hayden in Western Ame¬ 
rica, are several fossil specimens from the Judith River, which prove the former existence 
of a large herbivorous lizard, nearly allied to the great extinct Iguanodon of Europe. 
The specimens, consisting of the unworn crown of a tooth, and portions of several much- 
worn teeth, at the time they were sent to the author for examination, were noticed in the 
Proceedings of the Academy of Natural Sciences of this city, as characteristic of a new 
genus of extinct herbivorous saurians, with the name of traciiodon mirabilis. Subse¬ 
quently a large collection of remarkably well preserved remains of another huge saurian, 
closely allied to Traciiodon and Iguanodon , were obtained by our fellow member, W. Parker 
Foulke, Esq., from the green sand clay, in the neighbourhood of Haddonfield, New Jersey, 
not far distant from this city. The collection was presented by Mr. Foulke to the Aca¬ 
demy of Natural Sciences, and was the subject of a short communication, in which the ani¬ 
mal was characterized with the name of Iladrosaurus Foidlcii. 
Of the specimens of teeth referred to Traciiodon , the unworn crown is the most im¬ 
portant. It is represented in plate 9, figures 1—3, and is conical in form and slightly 
curved in its length. An examination of more perfect teeth of Iladrosaurus has led me 
to consider the specimen as having belonged to the lower jaw. Its inner face, (fig. 1,) is 
alone invested with enamel, is lozenge-shaped in outline, and is divided by a prominent 
median carina or ridge. The surfaces between the latter and the lateral borders of the 
crown are slightly depressed, smooth and shining. 
The upper borders of the lozenge-like enamelled surface are the longer, but are neither 
serrated nor tuberculated, though they are slightly rugose towards the outer aspect of the 
tooth. The apex of the latter as formed by the enamelled surface is rounded, the lateral 
angles are obtuse, and the inferior angle is notched. 
The portion of the tooth exterior to the enamelled surface is subtrihedral above and be¬ 
comes pentahedral below, (figs. 2, 3,). The lateral or innermost divisions of the pentahedral 
portion of the crown, apparently exhibit the impress of the summits of laterally succeeding 
teeth, (fig. 2, a,) and the remaining surfaces of the exterior of the tooth are roughened 
with granular tubercles. 
The broken base of the specimen is irregularly hexahedral in outline, and presents at 
its middle the open pulp cavity in the form of an ellipsoidal figure, with the long diameter 
VOL. xi.—19 
