134 CRUSTACEA—PERACARIDA CHAP. 
absent. Very large lamellae grow out from the bases of the 
thoracic limbs to form a brood-pouch, and in this manner the 
adult condition is attained. 
The final complication in the life-histories of these Isopoda 
is reached by the family Entoniscidae, which are parasitic when 
Fig. 92.—Bopyrus fougerouxt. A, 
Ventral view of female carrying a 
male (J/) between her abdominal 
appendages, x 8; 8B, ventral 
view of part of head of female, 
the maxillipedes and the left 
mandible having been removed. 
A.1, A.2, 1st and 2nd antennae ; 
M, male; Mn, right mandible ; 
Mz, left maxillipede ; O, ooste- 
gite; 7, left 4th thoracic append- 
age or 3rd leg. (After Bonnier.) 
adult inside the thoracic cavity of Brachyura and Paguridae. 
The cephalothorax of a Carcinus maenas, which contains an adult 
Portunion maenadis (P), is shown in Fig. 93. The parasite is 
of a reddish colour when alive. 
The Entoniscidae pass through a free living Epicaridian 
and Cryptoniscus stage, and become adult males in the Bopyrus 
stage. It is stated, however, by Giard and Bonnier! that these 
individuals, which actually function as males, never grow up 
1 Trav. Inst. Lille, v., 1887. 
