112 AIR. 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 Elapliocaris is the larva of Sergestes, and 

 he traced its development through the AcantJiosoma stage, which, from its resemblance 

 to Amphion, he calls the Amphion stage. 



These various observations, and especially those by GLAUS, give us a pretty complete 

 acquaintance with the metamorphosis of Sergestes from the first Protozoea stage to 

 maturity. 



The first Protozoea (GLAUS, ' Untersuchungen,' taf. v., fig. l) 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 niaxilla?, 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 endopodite 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 Protozoca 

 of Lucifer will be seen by a comparison of columns 1 and 3 of Table IV. 



The next stage which GLAUS 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 Iarva3 of Acetes and Lucifer. 



The thoracic limbs are represented \>j five pairs of rudimentary bilobed buds. There 

 are five free abdominal somites without appendages, and the sixth and telson are 

 represented by an unsegmented 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 V. with columns 1 and 2. 



In the next or Acantliosoma 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 flageUum of the 

 second antenna are well developed. 



The exopodites of the maxillipeds and pereiopods are very long, many-jointed, except 

 in the first rnaxilliped, 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 



