28 
to it. In the bodies of the smaller vertebre the epiphyses are 
wanting, and Mr. Owen agrees with Dr. Harlan in infering from the 
common occurrence of this condition, that there were originally 
three separate points of ossification in the body of the vertebree; a 
character never noticed in the vertebrz of Saurians, but a most pro- 
minent one in those of the Cetacea. Another argument in favour 
of the mammiferous and cetaceous nature of the Basilosaurus is de- 
duced from the great capacity of the canal for the spmal chord, 
which in the Cetacea is surrounded by an unusually thick plexiform 
stratum of both arteries and veins. ‘The cetaceous character is 
further manifested in the short antero-posterior extent of the neura- 
pophyses as compared with that of the body of the vertebre; in 
their regular concave posterior margin, and the development of the 
articular apophyses only from their anterior part: also in the form 
and position of the transverse processes, which however present a 
greater vertical thickness than in the true Cetacea, and approach in 
this respect to the vertebrze of the Dugong. 
With respect to the other bones of the Basilosaurus, Mr. Owen 
stated, that the ribs in their excentric laminated structure are pecu- 
liar, and unlike those of any mammal or Saurian. The hollow 
structure of the lower jaw of the Basilosaurus, which has been ad- 
vanced as a proof of its saurian nature, Mr. Owen showed occurs 
also in the lower jaw of the Cachalot, and is therefore equally good 
for the cetaceous character of the fossil. 
In the compressed shaft of the humerus, and its proportion to the 
vertebre, the Basilosaurus again approximates to the true Cetacea, 
as much as it recedes from the Enaliosaurians; but in the expansion 
of the distal extremity and the form of the articular surface, this hu- 
merus stands alone; and no one can contemplate the comparative 
feebleness of this, the principal bone of the anterior extremity, with- 
out agreeing with Dr. Harlan, that the tail must have been the main 
organ of locomotion. 
Mr. Owen, in compliance with the suggestion of Dr. Harlan, who, 
having compared with Mr. Owen the microscopic structure of the 
teeth of the Basilosaurus with those of the Dugong and other ani- 
mals, admits the correctness of the inferences of its mammiferous 
nature, proposes to substitute for the name of Basilosaurus that of 
Zeuglodon, suggested by the form of the posterior molars which re- 
semble two teeth tied or yoked together. 
A paper, ‘‘ On the Geology of the Neighbourhood of Lisbon,” by 
Daniel Sharpe,” Esq., F.G.S., was commenced. 
Jan. 23, 1839.—H. Sockett, Esq., Barrister at Law, Swansea; 
John Thomas Barber Beaumont, Esq., County Fire Office, Regent- 
street; and Rev. Thomas Rees, LL.D., F.S.A., Woburn-place, were 
elected Fellows of this Society, , 
A notice on ‘‘ the Occurrence of Graptolites in the Slate of Gal- 
loway in Scotland,” by C. Lyell, Esq., V.P.G.S., was first read. 
On examining some specimens of slaty sandstone and shale, col- 
lected by Mr. John Carrick Moore, on the shore of Loch Ryan in 
