82 
MR. W. K. BROOKS OK LUCIFER: 
behind them, and the fifth thoracic somite is entirely wanting, nor are its appendages 
present at any stage in the development of Lucifer. 
The abdomen is much longer than it was at the last stage, and all its segments 
(fig. 43, A 1, A 6) are present, although the last one (A 6) and the telson ( T) are not yet 
entirely separated. 
The ventral surface of the sixth abdominal somite is armed with a pair of long 
stout spines over the base of the swimmeret, or sixth abdominal appendage, which 
is shown in fig. 43 as a long, bilobecl pouch or bud, which reaches nearly to the tip 
of the telson. The third, fourth, and fifth abdominal somites carry, close to the anterior 
edge of the ventral surface, irregular groups of reddish-brown pigment-spots, which 
do not seem to be present in all specimens. The thoracic spots (fig. 44) and the 
anal spots (fig. 45) are usually a little more red than before, but they are nearly 
black in some specimens. The abdominal ganglia, which could not be distinctly made 
out in the last Protozoea, are now very conspicuous, as shown in the ventral view 
(fig. 43). They lie near the posterior edges of the somites, and their halves are 
united in the median line, although the commissures between the ganglia are quite 
widely separated. 
The spines on the telson have lengthened, but their number, arrangement, and 
relative size is the same as before. Their proximal ends from the base about half-way 
to the tip are marked by fine serrations, which appear to be short hairs, which have 
not been perfectly extended. 
Schizopod or Sceletina stage (Acanthosoma of Sergestes). 
Up to this time the mode of locomotion has been by means of short, jerking Naup- 
lius leaps, and the two pairs of antennae have been, as they were when the larva left 
the egg, the chief organs of locomotion. The structure of these appendages has 
remained extremely constant through all the moults, but they now change their 
character entirely, and lose their locomotor function. 
The change which is undergone by the larva at the end of the Zoea series is very 
much greater than it has been at any preceding moult, except that between the Naup- 
lius and the first Protozoea, and in some respects it is even greater than it was at that 
time. After the moult it is a Schizopod (Plate 6, fig. 50), about jimo ^ nc ^ 1 ^ on £’ 
with seven pairs of long jointed biramous swimming feet, fringed with long slender 
hairs. The swimmerets are also present as functional appendages, with long fringing 
hairs. 
This stage differs from those which have gone before in this, that it persists with 
slight change for several moults, while there has been considerable change at each of 
the preceding moults. It is shown from below in fig. 50, as it appears immediately 
after the moult which follows the stage shown in fig. 43. 
The figure was drawn from a Zoea which was captured at the surface of the ocean, 
