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posed to belong to the same animal. In the matrix of the vertebra 
from the Washeta river was a fossil corbula, common in the Alabama 
tertiary deposits, and specimens of nautilus, scutella, and modiolus of 
extinct and new species; sharks’ teeth have also been found in a similar 
rock in the vicinity of the locality from which the other collection 
was procured. Dr. Harlan was originally inclined, from the struc- 
ture of the teeth, to consider these fossil remains as having belonged 
to a marine carnivorous animal; but from an examination of the 
bones he was induced to conclude, that they were portions of a new 
genus of Saurians, for which he proposed the name of Basilosaurus. 
Dr. Harlan then briefly described a portion of an upper jaw of a 
Saurian discovered by a beaver trapper, on or near the banks of the 
Yellowstone river in the territory of the Missouri, imbedded in a 
hard blue limestone rock. On first inspection Dr. Harlan believed, 
from the structure of the teeth, the mode of dentition, and the po- 
sition of the anterior nares, the fragment belonged to an Ichthyo- 
saurus ; but as it differs entirely from that genus in having separate 
alveoli, and in the form and position of the intermaxillary bones, 
while it approaches in the latter characters the batrachian reptiles, 
he has formed for the fossil a new genus designated by the name of 
Batrachiosaurus. 
A paper was afterwards read, entitled, ‘‘ Observations on the 
Teeth of the Zeuglodon, Basilosaurus of Dr. Harlan,’ by Richard 
Owen, Esq., F.G.S. Hunterian Professor in the Royal College of 
Surgeons, London. 
During the recent discussions respecting the Stonesfield fossil 
jaws, one of the strongest arguments adduced and reiterated by 
M. de Blainville and others in support of their saurian nature, was 
founded on the presumed existence in America of a fossil reptile 
possessing teeth with double fangs, and called by Dr. Harlan, the 
Basilosaurus. To the validity of this argument, Mr. Owen refused 
to assent, until the teeth of the American fossil had been subjected 
to a re-examination with an especial view to their alleged mode of 
implantation in the jaw; and until they had been submitted to the 
test of the microscopic investigation of their intimate structure 
with reference to the true affinities of the animal to which they be- 
longed. The recent arrival of Dr. Harlan in England with the fossils, 
and the permission which he has liberally granted Mr. Owen of 
having the necessary sections made, have enabled him to determine 
the mammiferous nature of the fossil. 
Among the parts of the Basilosaurus brought to England by Dr. 
Harlan, are two portions of bone belonging to the upper jaw ; the 
larger ofthem contains three teeth; the other, the sockets of twoteeth. 
In the larger specimen, the crownsof the teeth aremore or less perfect, 
and they are compressed and conical, but with an obtuse apex. The 
longitudinal diameter of the middle, and most perfect one, is three 
inches, the transverse diameter one inch two lines, and the height 
above the alveolar process two inches and a half. The crown is trans- 
versely contracted in the middle, giving its horizontal section an 
hour-glass form; and the opposite wide longitudinal grooves which 
