PROCEEDINGS 
OF 
THE GEOLOGICAL SOCIETY OF LONDON. 
¢ 
Vou. III. 1838—1839. No. 60. 
Dec. 9, 1838.— A paper on the “ Phascolotherium,” being the 
second part of the ‘‘ Description of the Remains of Marsupial 
Mammalia from the Stonesfield Slate,’ by Richard Owen, Esq., 
F.G.S., was read. 
Mr. Owen first gave a brief summary of the characters of the 
“« Thylacotherium,”’ described in the first part of the memoir, and 
which he conceives fully prove the mammiferous nature of that 
fossil He stated, that the remains of the split condyles in the spe- 
cimen demonstrate their original convex form, which is diametrically 
Opposite to that which characterizes the same part in all reptiles 
and all ovipara ;—that the size, figure and position of the coronoid 
process are such as were never yet witnessed in any except a 
zoophagous mammal endowed with a temporal muscle sufficiently 
developed to demand so extensive an attachment for working 
a powerful carnivorous jaw;—that the teeth, composed of dense 
ivory with crowns covered with a thick coat of enamel, are every where 
distinct from, the substance of the jaw, but have two fangs deeply im- 
bedded in it ;—that these teeth, which belong to the molar series, 
are of two kinds; the hinder being bristled with five cusps, four of 
which are placed in pairs transversely across the crown of the teeth, 
and the anterior or false molars, having a different form, and only 
two or three cusps—characters never yet found united in the teeth 
of any other than a zoophagous mammiferous quadruped ;—that the 
general form of the jaw corresponds with the preceding more essen- 
tial indications of its mammiferous nature. Fully impressed with 
the value of these characters, as determining the class to which the 
fossils belonged, Mr. Owen stated, that he had sought in the next 
place for secondary characters which might reveal the group of 
mammalia to which the remains could be assigned, and that he 
had found in the modification of the angle of the jaw, combined 
with the form, structure and proportions of the teeth, sufficient 
evidence to induce him to believe, that the Thylacotherium was a 
marsupial quadruped. 
Mr. Owen then recapitulated the objections against the mammi- 
ferous nature of the Thylacotherian jaws from their supposed imperfect 
state ; and repeated his former assertion, that they are in a condition 
to enable these characters to be fully ascertained : he next reviewed, 
first the differences of opinion with respect to the actual structure 
VOL, III. c 
