Prof. Owen on the Class Mammalia, ~ 7 
This symbol affords no basis fer the commonly received idea 
that infinity means an absolute unboundedness, a quantity abso- 
lutely without end, a quality or nature transcending all bound- 
aries. Such an idea has no right in the mind of man, for the 
pee so far from stating an absolute ee end- 
lessness or illimitable ono ape Ale states simply the limitations 
f 
of finite perceptive pow t is the expression, not 0 
immeasurableness of nsiaea or of pe Deity, but of the finite 
limitations of the human mind. It stands for a negative and 
not for a positive: it symbolizes not seen ge but ignorance. 
if we group infinite attributes under a divine name, we have not 
defined Deity but we have defined the limits of our own concep: 
tions. The limits of our knowledge lie near at hand: the limits 
of our ignorance are known only to the All-knowing. 
Art. IL—On the Characters, Principles of Division, and ean 
Groups of the Class Mammalia; by Professor OwEN F.RS., 
| Se) ee eens of the Natural History Departinctitsel in 
the British Museum 
THE class Mammalia, the most highly organized of the animal 
kingdom and that to which we ourselves belong, appears to have 
been the class of animals last introduced on this planet, and not 
to have attained ee Pimete until the tertiary division 
1 of as Ney time. 
glands, and suckle their young: the embryo or foetus is 
Revaloced in the womb. Their leading anatomical character is 
to have lungs, composed of a highly vascular and minutely cel- 
lular structure throughout, and sus eee freely in a thoracic 
oy separated by a tec! and tendinous septum or dia- 
phragm from the abdom 
. Mammals, like birds, ee a heart composed of two ventricles 
and two auricles, and have warm blood: they breathe quickly ; 
but inspiration is performed chiefly by the agency of the dia- 
hragm ; and the ae air acts cae on the capillaries of the 
pulmonary circulation 
This paper is cited from the Journal of the Proceedings of the Linnean as 
ea aagll Pcead February 17th and April 21st, 1857 uz 
From mamma, a pap. The Platypus wf Echidna are the only known e 
gas to this rule. The Mare is an apparent one, from the a —— position of t 
nipples. The fetal Cetacea show tufts of hair on the m 
