xxii 
times many metres in height. It is then in the Ma- 
dreporic Polypidoms, those that are wholly stony, 
that we must seek for giants in this department of 
the animal kingdom ; whilst their Polypi are so small 
as frequently to elude the naked eye, and can only be 
perceived by the help of glasses, and sometimes re- 
quire very powerful microscopes ; in some groups 
they even escape the power of our instruments, and 
leave us only analogy and reason to demonstrate their 
existence in the animal kingdom. It is however not 
improbable that the Equinoctial seas may inclose 
Polypi of sufficient magnitude to be observed without 
the help of instruments ; but none of them exist on 
our coasts, or in the north of Europe. 
UTILITY, GENERAL AND PARTICULAR. 
The unreflecting may ask, what is the utility of 
these creatures ; too small to afford material nourish- 
ment to others, yet capable of rendering venomous 
those which partake of the little they can supply ? De- 
voured by fishes, the Polypi have rendered those 
fishes so unwholesome, that soldiers who have fed on 
them have experienced maladies so serious and so 
general, that the expedition for which they were in- 
tended has been necessarily given up. 
Other species of fish, and in particular the mollusca 
