Cuar, XVII MANNER OF CAPTURING PREY. 409 
“mind what I have witnessed when a small snake 
“makes a large frog its victim.” But as the valve 
does not appear to be in the least irritable, the 
slow swallowing process must be the effect of the 
onward movement of the larva. 
It is difficult to conjecture what can attract so many 
creatures, animal- and vegetable-feeding crustaceans, 
worms, tardigrades, and various larve, to enter the 
bladders. Mrs. Treat says that the larve just 
referred to are vegetable-feeders, and seem to have a 
special liking for the long bristles round the valve, but 
this taste will not account for the entrance of animal- 
feeding crustaceans. Perhaps small aquatic animals 
habitually try to enter every small crevice, like that 
between the valve and collar, in search of food or pro 
tection. It is not probable that the remarkable trans- 
parency of the valve is an accidental circumstance, 
and the spot of light thus formed may serve as a 
guide. The long bristles round the entrance ap- 
parently serve for the same purpose. I believe that 
this is the case, because the bladders of some epi- 
phytic and marsh species of Utricularia which live 
embedded either in entangled vegetation or in mud, 
have no bristles round the entrance, and these under 
such conditions would be of no service as a guide. 
Nevertheless, with these epiphytic and marsh species, 
two pairs of bristles project from the surface of the 
valve, as in the aquatic species; and their use pro- 
bably is to prevent too large animals from trying to 
force an entrance into the bladder, thus rupturing the 
orifice. 
As under favourable circumstances most of the blad- 
“ers succeed in securing prey, in one case as many as 
ten crustaceans ;—as the valve is so well fitted to 
