149 

 Genus LXXXIII. MONOCULUS. 



CxESTERIC CHARACTER. 



Antenna (in such species as have them) two, 

 simple, or branched ; those of the male thicker 

 and shorter. Eyes, in most species, approxi- 

 mated, and fixed in the shell. Body covered 

 with a crustaceous tegument. Feet formed 

 for swimming. 



General Observations. 



All the Monoculi with which we are acquaint- 

 ed are aquatic. They live in lakes and marshes, 

 and are often met with also in rivers. Their 

 manner of moving is very singular. They use 

 their branched antennae in the room of arms ; 

 and with their aid they advance in the water, 

 as it were, by starts or leaps. Their feet are 

 also employed for the same purpose, but arc 

 not so effective as the horns. Monoculi are 

 oviparous, and being transparent, the ovaria 

 in the female may be very plainly seen with- 

 in their crustaceous covering. Some carry 

 their eggs in a more exposed situation, near the 

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