72 ARTICLES REFERRED TO IN THE SECRETARY'S REPORT. 
When Dr. Mantell first exhibited teeth of the Iguanodon, no one would 
believe that they belonged to a reptile, and even Cuvier pronounced a worn 
specimen to be the tooth of a rhinoceros. 
The teeth of Hadrosaurus have the same general constitution as those of 
Iguanodon, being adapted to the trituration of vegetable food. They are 
exceedingly small in relation with the size of the animal, measuring only a 
little over an inch in length, but they were numerous, and appear to have been 
arranged so closely together as to form a continuous pavement at the border of 
the jaws, well adapted to the crushing and comminution of vegetable sub- 
stances. As the tecth in use were worn away, they were incessantly followed 
by others, which also appear to have been arranged in close apposition with 
one another. 
Hadrosaurus was probably an amphibious reptile. Its huge, laterally flat- 
tened tail was evidently adapted to swimming. The large hollows in the 
interior of the arms and thigh bones would indicate a partially terrestrial habit. 
The great disproportion between the fore and back parts of the body has led 
to the view that when not swimming the huge reptile supported itself in a frog- 
like position, though it had an additional prop in the huge tail. 
Teeth nearly like those of Hadrosaurus, but referred to another reptile, 
named Trachodcn, have been discovered by Dr. F. V. Hayden, in a formation 
of unascertained age, though probably cretaceous, in the bad lands of the 
Judith river, a tributary of the Missouri, near its source. 
Other huge bones of reptiles have been discovered in the New Jersey green- 
sand, of uncertain reference, but most probably of species allied to Hadrosaurus. 
Several bones, from Burlington county, of a reptile of comparatively small size 
with the latter, though also probably allied to it, are remarkable for their hol- 
lowness, almost approaching in this respect the condition of the bones of birds. 
They have been referred to a genus under the name of Celosaurus, the term 
referring to the hollowness of the skeleton. 
Several teeth of a large reptile, discovered in a eretaceous formation near 
Bladensburg, Maryland, have been referred by Dr. Johnson, of Baltimore, to a 
peculiar genus, under the name of Astrodon. 
A large tooth, mingled with a number of others of sharks, from the green- 
sand of Mullica Hill, Lancaster county, New J ersey, indicates a carnivorous 
reptile, to which the name of Tomodon horrificus is applied. 'The tooth re- 
sembles a large shark tooth, being broad, flattened conical, with sharp, cutting 
borders minutely serrated. The original possessor of the tooth was no doubt 
a fierce and sanguinary cotemporary of the peaceful, herb-eating Hadrosaurus. 
Of turtles, the green-sand of New Jersey has furnished the fossil remains of 
a number of genera and species. The fossils are, however, generally in a very 
imperfect state, usually consisting of fragments of a few plates of the bony 
shell. ‘The remains observed by the author appear to indicate eight species 
of five genera. Of these, two are referred to Chelone, three to Emys, one to 
Platemys, one to Trionyzx, and one to a peculiar genus—Bothremys. The latter 
is rematkable from the jaws being provided with large funnel shaped pits, one 
