13S 
NATURAL HISTORY OF 
GYRINUS, 
a word sometimes used by Aristotle and other Greek 
writers, and which is derived from a verb signifying 
to move in a circle . They afford a few well-marked 
characters, by which they are readily distinguished 
from all their aquatic associates. The antennae are 
short and thick, and are attached to the head in 
such a manner as to resemble ears. They consist 
of a clavate mass formed of seven closely joined 
rings, which is attached by a slender peduncle to 
the upper and internal edge of a large radical joint 
furnished with an auricle on its outer side, which, 
like the lid of a box, shuts in the antennae when 
unemployed, and protects them from the water** 
The anterior legs are long, and formed for walking, 
or to act as instruments of prehension ; the four 
hinder ones are very short, compressed and ciliated 
externally, bearing a strong resemblance to the 
paddle of an oar. The head is sunk in the thorax 
as far as the eyes, and the latter are divided by a 
process from the anterior part of the head, in such 
a manner that there appear to be two eyes above 
and two below — a mode of structure admirably 
adapted to the wants of the insect, which requires, 
at the same time, to observe objects both in the air 
and water. 
Kirby and Spence’s Introd. to Entom. iii. 516. 
