Cee 16. « 9} 
CLASS Hil. AMPHIBIA. 
Remarks. ‘The blood of animals is rendered 
warm and capable of exciting nervous action 
by the process of respiration. Amphibicus ani- 
mals have their circulatory system so arranged. 
that but a part of the bleod passes into the lungs ; 
consequently does not receive the benefit of free 
vespiration. The necessary deficiency in the 
warmth and in the exciting power ef the blood. 
predisposes them toa torpid state. And though 
some of them move with rapidity at times ; they 
are generally torpid, their digestion slow, their 
senses dull, and some of them pass the winter in 
a lethargic state. Even if the head is separated 
from the body, life is still manifested by muscular 
action fora long time. Their pulmonary vessels 
are so small, and respiration so slow, that they 
may remain long under water without producing 
any change in the circulation of the blood. 
ORDER 1. CHELONTA. 
Having a covering consisting of a sheli on the 
back and on the breast, and waliing or swimming 
with four feet. Heart with two auricles. 
Testuno, (tortoise,) body defended by a bony 
covering, or coated by a horny, scaly or coriaceous 
integument ; mouth with a sort of serrate mandi- 
bles, and not proper teeth ; the upper mandible 
closing over the lower. 
