565 



divided into eight joints, of which the two nearest the base are much 

 shorter than the others. The biramous mandible is less than one third 

 as long as the antennae. The endopodite is divided into three joints, 

 and terminates in two long hairs. The exopodite is unjointed and ends 

 with three hairs. There is no cutting blade. The labrum is very large, 

 and the telson is indicated by a fold on the ventral surface of the poste- 

 rior end of the body. The four appendages behind thé mandibles are 

 no more developed than they were at the earlier stage. 



At the end of twelve hours more the embryo, ^/looo ii^ch long, has 

 imdergone considerable change, although it is still a Nauplius. The 

 joints of the first antennae have disappeared, and those of the second 

 antennae are barely indicated. The setae of the second antennae and 

 of the mandibles are plumose, and the basal joint of the mandible 

 carrysa single, strong, curved, cutting hair. The telson is well marked, 

 and carrys six short strong spines. The outline of the posterior and 

 lateral edges of the carapace is now visible. 



The four pairs of appendages behind the mandibles are still rudi- 

 mentary. The general form of the Nauplius of Leucifer is much more 

 like Metschnikoff's figure of the Nauplius of Euphausia, than it is 

 like Fritz Miiller's figure of the Nauplius of Penaeus. 



At the end of the next twelve hours the larva, ^%ooo i^^ch long, 

 has undergone very great change, and resembles the youngest Euphausia 

 larva which Claus figures , although the edge of the carapace is 

 smooth and unserrated. 



The carapace makes about one half the length of the body. It is 

 horse-shoe shaped , with a rostrum , and a dorsal and two lateral 

 posterior spines. The frontal sense organ and ocellus are still present. 

 The heart gives rise to three anterior arteries, one on the median line, 

 and one on each side. The first antennae are uniramous and two- 

 jointed. The second antennae are biramous; the endopodite is un- 

 jointed, the exopodite jointed. The mandible is like that of the adult, 

 but has only one denticle. Behind it are two pairs of maxillae, with 

 scaphognathites , and two pairs of biramous maxillipeds , the second 

 pair rudimentary. 



The third pair of maxillipeds are wanting, but their body segment, 

 and the first four thoracic segments are present, and are followed by an 

 unsegmented abdomen, with five pairs of strong spines at its posterior end. 

 After the next moult the larva is ^Viooo inch long, and the outline 

 of the body has undergone considerable change, although the appen- 

 dages and segments are the same as before. The antennae are still the 

 chief locomotor organs, as they were during the Nauplius stage. The 

 ocellus is still present, and accumulations of pigment marke the posi- 

 tion of the compound eyes. 



