THE BOodA-CONSTRICTORS. 290 
the result being only a matter of time depending on their 
relative size. | 
In all the cases observed, the contests took place 
in the grass-covered swamp or marsh by the riverside, 
the alligator struggling fiercely with head, legs and 
tail, turning about, heaving and wriggling, in a vain 
endeavour to cast off the boa. It is remarkable that 
even when the alligator is of a size such that it might 
by wriggling reach the deeper water, it seems to avoid it, 
perhaps from the recognition that, in the water, where 
they would both sink to the bottom, its chances of 
holding out, under the pressure of the snake’s folds, would 
be lessened. 
On land, the continuance of the struggle depends on the 
crushing power of the boa, and the resistance of the alli- 
gator—dependent on its size—to suffocation—a process 
that in these mixed biooded creatures is only effe€ted with 
considerable difficulty. Possibly cases may occur where 
a small boa attempts the impossible and has eventually to 
abandon it ; but in those that have been under observation, 
the sizes have been such that, while by means of the head, 
tail and toes, the alligators have been able to toss and 
wriggle about to a greater or less extent, they were evi- 
dently under stress of partial suffocation. For loyg inter- 
vals they would remain perfe€tly still, perhaps from 
collapse, or with the expectation that the boas might con- 
sider them dead and proceed to unfold them: and then 
again they would struggle furiously, but equally to no 
effeat. 
It is a curious thing that under such circumstances, a boa 
will allow of quite close approach without its attempting 
to escape or attack if interfered with, and in faé& the 
Q2 
