84 
ME. W. K. BROOKS OK LUCIFER: 
equal in length, although even at this stage the endopodite is a little the longest. 
Each ramus ends with a pair of very short hairs. 
The appendage now changes with each moult, and in the third Schizopod stage 
(fig- 54) the exopoclite has become a scale (fig. 57, ex) while the endopodite ( en) has 
elongated, and now forms a seven-jointed flagellum, about as long as the first 
antennae or the carapace. The basal joint (fig. 57, b) is thick and swollen, the two 
proximal joints of the flagellum (2 and 3) are short; the next (4) long, and the other 
four about equal in length, and about half as long as the joint (4). 
Through all the Schizopod stages the structure of the labrum (L) is about as it was 
in the Protozoea and Zoea, and its interior angle is still produced into a short stout 
sharp spine. 
The mandibles are cutting jaws with no trace of a palpus, and at the first Schizopod 
stage (fig. 51) the denticles are numerous and of nearly uniform size. In the last 
Schizopod stage (fig. 58) a second set of denticles has appeared on the outer surface 
of the blade a short distance from the cutting edge. 
The first maxilla (fig. 52) is very much like that of the Protozoea and Zoea, but the 
cutting hairs upon the two basal joints (l and 2) are more numerous, and a small 
slender plumose hair has appeared near the edge of each joint. The scaphognathite 
is small and has only two hairs, which are less regularly plumose than before. 
The scaphognathite of the second maxilla (fig. 53, sc) is now rudimentary and has 
no hairs. The hairs on the inner edge of the appendage are shorter than they were 
during the Zoea stage, and all of them are plumose and about equal in length. 
The first maxilliped (fig. 50, Mp. 1) has not changed very much, although its joints 
are nearly absent. The exopodite is about as long as the endopodite, and all the hairs 
on the appendage are short and plumose. 
The second and third maxillipeds and the four pairs of thoracic appendages are well 
developed, as a series of long biramous or Schizopod feet, which are essentially alike in 
form and structure, and, with the telson and swimmerets, now form the locomotor 
apparatus of the larva, which no longer swims by jerks but darts through the water 
with great rapidity, and is able to offer considerable resistance to the suction of a 
dipping tube. Each swimming foot consists of a two-jointed basal portion or protopo- 
dite, a long four-jointed endopodite, and a much shorter exopodite. The exopodite is 
flat, pointed, and its outer or distal half is marked by a series of six pairs of notches, 
or annulations, close together. The terminal joint carries a pair of long slender 
unplumose hairs, and a pair of similar hairs springs from each annulation, so that there 
are fourteen hairs in all on each exopodite, arranged so as to form a large fan-shaped 
paddle at the tip of the limb. The terminal joint of the endopodite is much shorter 
than the others, and it carries six long plumose hairs. The first appendage in this 
series, the second maxilliped (fig. 59, Mp. 2), is somewhat rudimentary: the endopodite 
is scarcely longer than the exopodite, and its hairs are short. The next or third 
