70 ARTICLES REFERRED TO IN THE SECRETARY S REPORT. 
diggings of the marl. Some of the specimens of teeth exceed six inches in 
length, but generally they are smaller. 
The teeth present considerable variety, generally having curved conical or 
pyramidal crowns, frequently more or less compressed, with the surfaces in 
different degrees subdivided into narrow planes or nearly or quite devoid of 
them. The root or fang is cylindrical and several times the bulk of' the crown, 
and is inserted in a deep socket witl which it is usually observed firmly co-os- 
sified, though it may also be loose, depending on the age or state of development 
of the tooth. New teeth were incessantly developed as those in use were 
worn away. They made their appearance at the back part internally of the 
fangs of the latter, and their fangs were gradully hollowed to accommodate 
the growth of the new teeth. The crowns of the old ones were then shed to 
allow the new ones to occupy their place, and after the full growth of the new 
teeth their fangs co-ossified with their containing sockets. A constant succes- 
sion of teeth in this manner took place during the life of the Mosasaurus. 
The remains of the New Jersey Mosasaurus have been referred to a species 
named M. Mitchilli, in honor of Dr. S. L. Mitchill, of New York, who first 
directed attention to their existence in this country in 1818. A few fossils, 
apparently of the same species, have been found in North and South Carolina. 
Remains of Mosasaurus, probably of a different species from the former, have 
been discovered on the Upper Missouri, of which a notice was first given by Dr. 
R. Harlan, in 1834. The greater part of a skeleton was subsequently found 
by Major O’Fallon, imbedded in a rock in the vicinity of Big Bend, and was 
presented by him to Maximillian, Prince of Wied, who was then travelling in 
western America. The prince had the specimen conveyed to Europe and pre- 
sented to the Academy of Naturalists at Bonn, in the museum of which it is 
now preserved. Dr. Goldfuss, who described the specimen, estimated the num- 
ber of vertebree to have been one hundred and fifty-seven. We have but little 
certain knowledge of the bones of the limbs of Mosasaurus; but the more 
authentic specimens which have been found go to show that the animal was 
provided with fins adapted to swimming. 
Remains apparently of a comparatively small species of Mosasaurus, or of 
a closely allied genus, have been discovered in the cretaceous formations of 
Alabama and Mississippi. 
Some isolated vertebre of large size, from the green-sand of New Jersey, are 
supposed by Professor Owen, of London, to indicate a saurian distinct from 
Mosasaurus, though allied to it, to which he has given the name of Macrosaurus 
levis. Similar vertebree have been found in North Carolina. <A long, narrow, 
conical tooth crown, with the surfaces subdivided into planes, from the green- 
sand of Burlington county, New Jersey, and an exactly similar one from the 
shores of Cape Fear river, North Carolina, indicate another reptile, probably 
allied to Mosasaurus, which have been named Polygonodon vetus. 
Perhaps the most extraordinary reptile yet discovered in the American creta- 
ceous formations is an enormous herbivorous lizard, the Hadrosaurus Foulki. 
A gentleman of Philadelphia, W. Parker Foulke, while passing the warm season 
