74 MR. W. K. BROOKS ON LUCIFER: 



When the embryo is set free from the egg it is seen to be inclosed by a delicate 

 cuticle, which is shown, around the antennae, in figs. 23 and 24. It is soon stripped 

 off by the vigorous movements of the larva, and in fig. 24 it has been torn from all 

 the appendages except the first antennae (A). 



In a dorsal view a number of muscular fibres are seen to extend outwards and 

 forwards from the median line of the body to the basal joints of the antennae. 



The posterior end of the body is not notched, the anus is absent, and there is no 

 trace of the telson or of the carapace. 



The first free Nauplius stuye. 



About thirty-six hours after oviposition the larva escapes from the egg as a Nauplius, 

 T~oou ulcn l n g> which is shown in side view in Plate 3, fig. 25. There is now no 

 difficulty in keeping it alive and rearing it, and it swims very actively by vigorous 

 strokes of its two pairs of antennae. Its movements are very characteristic, and much 

 like those of a Copepod or Cirrhiped Nauplius. 



The most important differences between it and the egg Nauplius are the segmenta- 

 tion of the locomotor appendages, the lengthening of their hairs, the increased size 

 and dendritic form of the pigment-spots (p), and the appearance of the telson (77), as 

 a projecting fold furnished with two pairs of short spines or hairs, in the ventral 

 surface of the posterior end of the body. 



As regards the more minute structure of the appendages, the first antennas (fig. 25, .4) 

 are five jointed, and the hairs, which are more than half as long as the limb, are 

 borne on the terminal joint. 



The second antenna consists of a two-jointed basal portion or protopodite which 

 carries two rami, one of which (fig. 25 ex), is obscurely divided into three nearly equal 

 joints, while the other (fig. 25, en), is divided into eight very distinctly marked joints. 

 Both at this stage and later the appendage possesses considerable power of rotation, 

 and sometimes the branch ex, and sometimes the branch en, is on the outer surface. 

 It is therefore very difficult to decide from an examination of this appendage alone 

 which branch is the exopodite and which the endopodite ; but, as I shall show further 

 on, a comparison with other appendages at a later stage indicates that the eight- 

 jointed ram us is the endopodite, although the limb is frequently, and perhaps 

 generally, carried in a position which brings this branch on to the outside. At this 

 stage the locomotor hairs of both branches are confined to the tips of the terminal 

 joints. The first and second joints of the endopodite are quite short, while the other 

 six are longer and nearly equal in length. 



The mandible consists of a short unjointed basal segment, which carries a one- 

 jointed endopodite, and an obscurely three-jointed exopodite. Each branch carries 

 three hairs, which are somewhat longer than the limb, and the entire length of the 

 appendage, including the hairs, is about equal to the length of the first or second 



