THE 
CANCROID MONOCULUS. 
Generic Character. 
Feet formed for fvvimming. 
Body covered by a cruftaceous fhell. 
Eyes (in moil fpecies) approximated. 
Specific Character, &e. 
MONOCULUS with convex fhell rounded in 
front, truncated behind: the tail furnifhed 
with two briftle-fhaped procelTes. 
Le BINOCLE a queue en filets. 
GeoffFUJI. abr. 2. p. 6fio. pi. 21. f 4. 
INSECTUM aquaticum, &c. 
Phil. Tranf. vol. 40. p. 150, &c. 
pi. 1. f 2. 
This curious infect is by far the largeft of all the 
European Monoculi; exhibiting with great diftindt- 
nefs the numerous branchiae and other parts which 
in the fmaller fpecies are only to be viewed by the 
abidance of the microfcope. The Linnaean genus 
Monoculus has by Fabricius, Muller, and others 
been 
