ME. W. K. BROOKS ON 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, bilobed 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 sepai'ated. 



The spines on the telson have lengthened, but their number, arrangement, and 

 relative size is the same as before. Their pi-oximal 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 (Acanthosorna 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 Zoca series is very 

 much greater than it has been at any preceding moult, except that between the Naitp- 

 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 y^g^ inch long, 

 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 Zoca which was captured at the surface of the ocean, 



