GERIUyj-, 
Genus VI ,—Gerinus* 
X HERE are only two Ipecies belonging to this family of 
Infers; the Natator and the Americanus ; both eafily dif- 
tinguilhed by their form, as well as their manners- The 
antennae are clavated, ftiff, and fhorter than the head: 
The hinder legs are alfo Ihort, flat, and very broad. 
Thefe animals are faid to have four eyes *, two on the 
upper and two on the under fide of the head ; they ap- 
pear in faft, on both fides of the head, but their number 
is only two; 
The gerinus natator has an Englifa name, being known 
in this country by that of the water-flea. It is that fmall 
animal which is feen defcribing circles on the furface of the 
water, by running on it with great fwiftnefs. When an 
attempt is made to take it, it plunges below and eludes 
the grafp. Tire larvae are faid to be found together 
with thofe of the dytifcus, an animal confiderably 
larger. 
The colour of the water-flea is a refplendent black, 
with a ihade of brown: Hie elytra are adorned with 
beautiful ftiiae, confiding of a number of points fo mi- 
nute, as hardly to be obferved without the afliflance of 
a microfcope. On the hinder part of the margins of 
Jie elytra are feen, by the fame means, fmall protube- 
rances. 
5 Syftcaia Nature, 
