Figure lo. — Celochilus septentrtonalis. (After Grobben, from Faxon.) 

 Copepoda, Natantia. Nauplius; Just hatched ; ventral view. 



Figure 14. — Adheres pcrca rum. (After Claus, from Faxon.) Co- 

 pepoda, Parasitica. Larva at the time it leaves the egg, with only two 

 anterior unbranched pairs of appendages of the typical naujilius piesent. 

 Under the skin are the rudiments of six pairs of appendages ; ///, man- 

 dibles; / F, niaxillsB ; V, F/, inaxilte; VII, F7/7, swimming feet. 



Figure 15. — Bahinus balanoides. (After Hoek, from Faxon.) Cirri- 

 pedia. Naujilius. 



Figure Iti. — Leniaidisi:ufi porcellanm. (After F. MUller, from Faxon.) 

 Cirripedia, Khizocephala. Nauplius ; ventral side ; showing outline of 

 dorsal shield. 



Figure 17. — SaccuVma purpurea. (After F. Midler, from Huxley and 

 Balfour.) Cirripedia, Rliizocephala. 



P'lGURE 18. — Cyj/rus ovum. (After Claus, from Faxon.) Ostracoda. 

 First larval (nauplius) stage, with bivalve shell and unbranched second 

 and third pairs of appendages. 



Figure 19. — Nebalia Geoffroiji. (After Metschnikoif, from Faxon.) 

 Leptostraca. Side view of the so-called nauplius stage of tlie embryo 

 within the egg. Rudiments are present of the two pairs of antennje (/, 

 //) aud the mandibles {III). 



Figure 20. — Euphauski. (After Metsohnikoff, from Faxon.) Schi- 

 zopoda. Nauplius ; just hatched. 



Figure 21. — Euphausia. (After Metsohnikoff, from Faxon.) Schi- 

 zopoda. Nauplius at a later stage; ventral view ; mt, metastoma; IV, V, 

 maxillEe ; VI, maxilliped. In the next, or Protozoen, stage the append- 

 ages (IV, V, VI) are true phyllopodiform feet. 



Figure 22. — Mysis ferruginea. (After Van Beneden, from Faxon.) 

 Schizopoda. Nauplius-like embryo ; side view. The apjiendages are 

 unsegmented, and the third pair is quite rudimentary. A number of later 

 metamorphoses are undergone in the nauplius skin, until tlie full number 

 of appendages is developed. 



Figure 23. — Peneun. (After F. Midler, from Faxon.) Decapoda, 

 Macroura. Nauplius; from dorsal side. 



Figure 24. — Lucifer. (After Brook.s, from Faxon.) Decapoda, Ma- 

 croura. Ventral view of embryo artificially removed from the egg ; 1 V, 

 V, VI, buds representing the two pairs of maxillse and first pair of max- 

 illipeds of the adult. 



Figure 25. — Palcemon. (After Bobretzky, from Faxon.) Decapoda, 

 Macroura. Nauplius stage of embryo within the egg. 



Figure 26. — Aiilacm Jlucialilis. (After Reichenbach, from Faxon.) 

 Decapoda, Macroura. Nauplius stage of embryo.' 



Figure 27. — Limulus polyphemus. (After King.slcy.) Xiphosura. 

 Ventral view of embryo ; showing the budding of the legs. 



Figure 28. — Limulus polyphemus. (After Packard, from Balfour.) 

 Xiphosura. Venti-al view of embryo in the egg ; showing the rudiments 

 of six pairs of legs ; m, mouth. 



Figure 29. — Limulus pnlypliemux. (After Packard, from Balfour.) 

 Xiphosura. Oblique side view of embryo, with the mouth and rudimen- 

 tary limbs ou the ventral plate. 



The figures of embryonic Limulus are introduced for comparison. 

 They are so different from the nauplius that detailed notice seems un- 

 necessary. 



