PARASITISM AND DEGENERATION 195 
itself to some stone or shell, or pile or ship’s bottom, loses 
its compound eyes and feelers, develops a protecting shell, 
and gives up all power of locomotion. Its swimming feet 
become changed into grasping organs, and it loses most of ' 
its outward resemblances to the other members of its class 
(Fig. 123, e). 
Fig. 123.—Three adult crustaceans and their larve. u, prawn (Peneus), active and 
free-living ; b, larva of prawn; ¢, Sacculina, parasite; d, larva of Sacculina ; 
e, barnacle (Lepas), with fixed quiescent life; J, larva of barnacle.—After 
HAECKEL. 
Certain insects live sedentary or fixed lives. All the 
members of the family of scale insects (Coccide), in one 
sex at least, show degeneration, that has been caused by 
quiescence. One of these coccids, called the red orange 
scale (Fig. 124), is very abundant in Florida and California 
and in other orange-growing regions. The male is a beau- 
tiful, tiny, two-winged midge, but the female is a wingless, 
