. [ * 9 8 ] 
to come afhore, the blood finds its paflage again 
through the lungs the moment he refpires. 
Thus the foetus in utero, during his confinement, 
having the lungs comprefled, and confequently the 
pulmonary arteries and veins impervious, has the cir- 
culation of the blood carried on through the oval hole 
and the arterial canal.; now fo far the phoca in the 
water and the foetus in utero are analogous; but they 
differ in other material circumfiances : one is, that the 
foetus, having never reipired, remains fuificiently 
nourished by the maternal blood circulating through 
him, and continues to grow till the time of his birth, 
without any want of refpiration during nine months 
confinement ; the phoca, having refpired the moment 
of his birth, cannot live very long without it, for the 
reafons given before; and this hole and canal would 
be doled in them, as it is in land animals, if the dam 
did not, very foon after the birth of the cub, carry him 
into the water to teach him, fo very frequently ; by 
which pra&ice thefe pafiages are kept open during 
life ; otherwife they would not be capable of attaining 
the food defigned for them by providence. 
Another difference is, that the phoca, as I faid before, 
would be relaxed by maceration in remaining too long 
in the water; whereas the foetus in utero lufiers no 
injury from continuing its full number of months in 
the fluid he fwims in : the reafon is ; that water is a 
powerful folvent, and penetrates the pores of the fkins 
of land animals, and in time can dilfolve them ; 
whereas the liquor amnii is an infipid foft fluid, im- 
pregnated with particles more or lefs mucilaginous, 
and utterly incapable of making the leaft alteration in 
the cutis of the foetus. 
4 
Otters, 
