502 
ONISCUS. 
Among the marine insects of this genus the 
largest is the Oniscus EntomoHy measuring two 
inches in length: its general form and colour re- 
sembles that of the O : Asellus, but the four lower 
pair of legs are longer in proportion, the three 
first pair being very small and short: the tail is 
long and pointed. It is a native of the Euroj^ean 
seas, and is found about rocks, &c. It is of a 
strong fabric, the divisions of the upper part being 
of an almost calcareous nature. This animal is 
capable of living several days in fresh water. 
