160 CRUSTACEA——EUCARIDA—DECAPODA CHAP. 
behind is converted into the Protozoaea (Fig. 107), possessing two 
pairs of biramous maxillipedes. It should be noted that the 
maxillae, which are foliaceous in the adult, are laid down in this 
Fria. 107.-—Protozaea larva of Peneus, sp. x 25. 
(From Balfour, after F. Miiller.) 
Fie. 108.—Zoaea larva of Peneus, 
condition in the larva, and this prin- gp, x 25. A, A’, Ist and 2nd 
ciple “holds good throughout, Cras-\ 5 menses Ab6 Guy abdonmnal 
2 : appendage; Map, 2nd maxilli- 
tacean metamorphosis, viz. that when pede; 7’, 4th-8th thoracic append- 
a limb is foliaceous in the adult it ie wallcing Lees $i ree 
is folaceous in the larva, and when 
biramous in the adult it is biramous in the larva. Whilst the 
rest of the thoracic limbs are still rudimentary, the sixth pair of 
pleopods are being precociously developed (Fig. 108), being the 
only precociously formed limbs in the Peneidea, though the abdo- 
minal segments are fully marked off before the thoracic segments, 
and so must be considered as precocious in development. When 
