458 
TRANSFORMA TIONS OF INSECTS. 
the anterior are simple, and the other two branched (biramose). 
These Nauplii have no carapace, no paired eyes, no masticating 
organs, and the mouth is over-arched by a helmet-like hood. 
This rudimentary larva or Nauplius soon alters in shape, moults, 
and a fold of skin grows across the back behind the third pair of 
feet, and four pairs of stout processes (rudiments of new limbs) 
sprout forth on the ventral surface. Within the third pair of feet 
powerful mandibles are developed. In a subsequent moult the new 
YOUNGEST NAUPLIUS OF A PRAWN. 
Magnified 25 diameters (after F. Muller). 
limbs (maxillae and antennae and intermediate maxilipedes — foot 
jaws) come into action, and the Nauplius becomes a Zoea , agreeing 
perfectly with the Zoea of the crabs in the number of the appendages 
of the body, although very different in form and mode of locomo- 
tion, and even in many particulars of internal structure. The 
chief organs of motion are still the two anterior pairs of feet 
which are slender, and furnished with long setae or hair-like spines. 
The third pair of feet loses its branches, and becomes converted 
into mandibles destitute of palpi. 
The labrum acquires a spine directed forwards, and of consider- 
able size, and the two-branched foot jaws appear to assist but 
