dcnly withdraw into the larger or exterior tubes, 
and in a moment or two afterwards again ex¬ 
tend themfelves: they even feem impatient of con¬ 
finement, and are commonly feen with the heads ex¬ 
panded, in which ftate their general fhape and mo¬ 
tions may be obferved with the naked eye; and 
indeed the fize of this animal is fuch as not to re¬ 
quire the affiftance of powerful magnifiers, but may 
be viewed to confiderable advantage by a lens of an 
inch focus; though in order to examine with accu¬ 
racy its feveral parts it is neceffary to make ufe of a 
microfcope. 
Thefe beautiful Zoophytes may be found during 
the Summer months in various waters in the neigh¬ 
bourhood of the Metropolis : the fpecimens repre- 
fented on the prefent plate w r ere difcovered in the 
water by the fide of the Willow-Walk at Chelfea, 
in which, as well as in feveral of the neighbouring 
waters, may alfo be found the Hydra viridis or com¬ 
mon green Polype. 
