118 
MR, W. K. BROOKS ON LUCTFER: 
Lucifter, so far as the form and number of the appendages is concerned; but the last 
pair of buds are biram ous, and the carapace and telson are well developed. The next 
stage (fig. 5) of the second paper is more advanced in nearly every respect than the 
second free Nauplius or meta -Nauplius of Lucifer. The mandible is rudimentary, but 
still bilobed, with no trace of a blade. The outline of the carapace is free from the 
body, and its anterior and posterior edges are spiny. It has frontal organs, and the 
basal joint of the second antenna carries five recurved hooks. 
According to the author, figs. 2 and 3 of the first paper show the next stage; but 
the structure of the hairs on the antennae, the fact that they are plumose, and the 
very deep notch in the telson, seem to indicate that this is another species. However 
this may be, the structural complexity at this and the next (first paper, fig. 6) stage 
is much greater than we find it in Lucifer at the end of the Nauplius series. 
It will be observed that, while Metschnlckoff’s larva and the Nauplius of Lucifer 
are essentially alike, there is at no time an actual agreement, since certain structures, 
as the carapace, become developed earlier, and others, as the labrum, later than they 
do in Lucifer; and certain structures, as the frontal organs and the hairs on the base 
of the antennae, are entirely absent in Lucifer. 
In column 4 of Table II. I have compared fig. 4 of Metschnickoff’s second paper 
with the first free Nauplius of Lucifer, and in column 3 of Table III. his fig. 5 with 
the last Nauplius stage of Lucifer. 
The various Protozoea stages are shown by Claus in plate 1 of the “ Unter- 
suchungen,” &c. The early Protozoea (Table IV., column 5) is much like that of 
Lucifer , but the carapace is serrated, there is only one pair of maxillipeds, and, 
according to Claus there is a fifth thoracic somite. In the last Zoea stage (Table V., 
- 
column 5) all the abdominal somites and the rudimentary swimmerets are present, but 
there is no trace of the second and third pairs of maxillipeds or of the pereiopods. 
Up to this point the course of development has followed essentially the same line 
as in the Sergestidce, but, as we should expect, the Protozoea series is not followed by 
a larval Schizopod stage, but by a series of moults during which the adult characteris¬ 
tics are gradually acquired. In the loss of the posterior spine of the carapace, the 
acquisition of antero-lateral spines, and the change in the antennae from the Nauplius 
form to the adult form, the moult is like that of Pemeus and the Sergestidae; but the 
second and third maxillipeds and the pereiopods appear one at a time in succession 
from in front backwards, and the abdominal feet appear before the pereiopods. There 
is no Zoea stage it is true, but the course of development differs from that of Penceus 
and the Sergestidae in the very feature in which the larvae of these forms differ from 
a typical Zoea —the irregular manner in which the pereiopods appear. 
I am therefore unable to give Claus’s interpretation of the significance of these 
larvae unqualified acceptance at present, and feel that our groundwork in this depart¬ 
ment of knowledge can be made sure only by new observations. Every naturalist 
who can trace the whole life-history of a single species of any of the genera of lower 
