IIS MR. W. K. 15BOOKR ON LUCTFER : 



Lucifer, so far as the form and number of the appendages is concerned ; but the last 

 pair of buds are biramous, 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 rciQizi-NaiipHus 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, seern 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 METSCHNICKOFF'S larva and the Nauplins 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 Protozoca stages are shown by GLAUS in plate 1 of the " Unter- 

 suchungen," &c. The early Protozoca (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 GLAUS there is a fifth thoracic somite. In the last Zoca 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 Sergcstidce, but, as we should expect, the Protozoca 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 PCIKBUS and the Sergestida? ; 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 Zoca stage it is true, but the course of development differs from that of Penaus 

 and the Sergestidas in the very feature in which the larvaB of these forms differ from 

 a typical Zoca the irregular manner in which the pereiopods appear. 



I am therefore unable to give CLAUS'S interpretation of the significance of these 

 larva? 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 



