NOTES ON THE WHIRLIGIG BEETLE. 69 
each in small light boats. One has long oars for rowing, the 
other is provided with a short paddle. The one with the paddle 
will make greater progress than the one with the oars. The 
man with the paddle, too, will have more control over his boat 
as regards turning or stopping dead than the man with oars. So 
it is with Gyrinus versus Dytiscus. A well-prepared microscope 
slide of an expanding paddle of Gyrinus reveals at once its 
marvellous structure, when viewed under a low power ; it is, 
moreover, one of the most beautiful objects that fall to the lot of 
the microscopist. The paddles, too, are aided in their work by 
long, stiff hairs which fringe them. ‘The second or middle pair of 
legs are expanded as well, though in a less degree. The first 
pair of legs are in a way no less wonderful than the paddles. 
They are prehensile, and when not in use are kept tucked away 
out of sight. In the male the tarsal joint bears sucker-like 
organs, which are thought by some writers to be of use in the 
detention of the female, and probably this theory is the correct 
one. 
Whirligigs possess a certain amount of curiosity, and will 
stop in their peregrinations to examine any object that lies 
in their path. I noticed once, when watching these insects, a 
piece of lichen fall from a tree near by into the water. This 
immediately attracted two or three beetles, which stopped to see 
what it was, and if they examined this once they did so a score 
of times during the brief space of time I watched them. A 
Whirligig beetle taken on March 24th, 1910, I confined in a 
glass of clear water. This particular specimen, contrary to the 
others mentioned above, made no attempt to leave the glass, but 
swam round and round beneath the water, hardly stopping a 
moment, forthe space of three hours or so, greatly upsetting the 
equilibrium of a number of a species of gnat larve confined in 
the same vessel. It made no attempt, however, to prey upon its 
fellow-prisoners, and at sunset became inactive, almost sluggish 
in its movements, at length sinking to rest tightly clinging 
to a piece of weed which, in spite of severe shaking of the 
glass, it refused to quit. As the cold of evening advanced, it 
seemed to sink into a state of coma. The following day being 
cold it remained in the same state. 
Gyrinus is in a singularly happy condition to bid defiance to 
