112 
MR. W. K. BROOKS ON LUCIFER: 
From independent researches in the South Pacific, Willemoes-Suhm also ascertained 
(Proc. Royal Soc., Dec. 9, 1875, p. 133) that Elaphocaris is the larva of Sergestes, and 
he traced its development through the Acanthosoma stage, which, from its resemblance 
to Amphion, he calls the Amphion stage. 
These various observations, and especially those by Claus, give us a pretty complete 
acquaintance with the metamorphosis of Sergestes from the first Protozoea stage to 
maturity. 
The first Protozoea (Claus, * Untersuchungen/ taf. v., fig. 1) has, like the Protozoea 
of Lucifer, locomotor antennae, a spine on the labrum, a partially segmented hind 
body, and a very spiny telson. The mandibles, first and second maxillae, and first 
and second maxillipeds are like those of the corresponding Lucifer larva. In addition 
to the spiny carapace it presents the following conspicuous differences from the Lucifer 
larva. The eyes are stalked, movable, and compound. The first antenna has seven 
joints. The enclopodite of the second antenna has no small rings at its base. There 
is a third pair of maxillipeds. Five thoracic somites are represented in the figure. 
The telson is very deeply cleft. The relation between the larva and the first Protozoea 
of Lucifer will be seeu by a comparison of columns 1 and 3 of Table IV. 
The next stage which Claus describes (taf. vi., fig. 1) is no doubt separated from 
the first by one or more intermediate stages. The rostrum has developed a pair of 
long secondary compound spines at its base, which do not correspond to anything in 
the corresponding larva) of Acetes and Jjucifer. 
The thoracic limbs are represented by five pairs of rudimentary bilobed buds. There 
are five free abdominal somites without appendages, and the sixth and telson are 
represented by an unsegmentecl region, which carries a pair of long bilobed pouches, 
the rudimentary swimmerets. 
The relation between Elaphocaris and the corresponding larvae of Acetes and Lucifer 
may be understood by a comparison of column 3 of Table Y. with columns 1 and 2. 
In the next or Acanthosoma stage (‘ Untersuchungen,’ taf. v., fig. 6) the two pairs of 
antennae assume the adult form, and the thoracic limbs and swimmerets become 
developed as they do in Lucifer, and the carapace loses its posterior spines, although 
there are three in place of one pair of anterior spines. The telson is distinct from the 
last abdominal somite, and all the abdominal somites have projecting spines. 
The eye-stalks are much longer than they are in the other two forms. The first 
antenna has a secondary flagellum, as in Acetes, and the scale and flagellum of the 
second antenna are well developed. 
The exopodites of the maxillipeds and pereiopods are very long, many-jointed, except 
in the. first maxilliped, and they are longer than the endopodites in all the pereiopods. 
The fifth pair of pereiopods are present and like the others. The swimmerets are 
very long and slender, and the telson very short and forked. 
This stage, like the corresponding stage of Lucifer, and unlike that of Acetes, 
persists for more than one moult, and the five pleopods make their appearance 
