Figure 13. — Cetochilusse/Jtentrionalis. (After (Iroltbeii, fiuiii Faxon.) 

 Copepoda, Natantia. Nauplius; just hatched ; veulral view. 



FiGUKK 14. — Adheres pcrcdruiii. (Alter t'huis, from Faxon.) Co- 

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

 anterior unbraiiched [)air.s of appendages of the ty[iical nanpliiis prescait. 

 L'nder the skin are the rudiments of six [)airs of appendages ; ///, man- 

 dibles; / r, ma.xilliie ; V, T/, maxilUe; VII, F///, swimming feet. 



FiGUUK 15. — Liahinus bulanoides. (After lloek, from Faxon.) Cirri- 

 pedia. Nauplius. 



FiGUKK Itj. — Leriucdiscus porcelldiue. (After F. Midler, from Faxon.) 

 Cirrijiedia, Uhizocephala. Nauplius; ventral side; showing outlim; of 

 dorsal shield. 



FuiUKK 17. — Scu:cuHn(i purpurea. (After F. INliillei', from Huxley and 

 Balfour.) Cirripedia, Jvhizocephala. 



F'iGUKE 18. — Ci/jirus arum. (After Claus, from Faxon.) Ostracoda. 

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

 and third pairs of ap[)endages. 



J'luuuE 19. — Nchulid Ueoffroiii. (After Metschnikoff, from I^axon.) 

 Lcptostraca. Side view of the so-called nauplius stage of the embryo 

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

 11) and the numdibles (///). 



Figure 20. — Euphausia. (After Metschnikolf, from ]'"axon.) 8chi- 

 zopoda. Nauplius; just hatched. 



Figure "21. — Eajihdusta. (After IMetschnikoff, from Faxon.) Schi- 

 zopoda. Nauplius at a later stage ; ventral view ; ?»/, mctastoma; / F, F, 

 luaxilhe ; Vf, maxillipetl. In the next, or Protozoen, stage the append- 

 ages (IV, V, VI) are true {)hyllo}Hjdiform feet. 



Figure 22. — M;jsis ferrui/ineu. (After Van Beneden, from Faxon.) 

 Schizopoda. Nau])lius-like eml)ryo ; side view. The a])pendages are 

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

 metamorphoses are undergone in the naui)lius skin, until the full number 

 of appendages is developed. 



F'iGUUE 2o. — Peneus. (After F. Muller, from Faxon.) Dccapoda, 

 Macroura. Naujilius; from dorsal side. 



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

 croura. Ventral view of end)ryo artificially removed from the (}gg; IV, 

 V, VI, buds rei)resenting tlie two pairs of maxilla! and first jiair of max- 

 illipeds of the adult. 



FiGUitE 2o. — Pdlmnnn. ('After FKjbretzky, from Faxon.) Decapoda, 

 Macroura. Nauplius stage of embryo within the egg. 



Figure 26. — Axtacus jlurkilUis. (After lleichenbaeli, fiom Faxon.) 

 Decapoda, Macroura. Nauplius stage of embryo. 



FiGiMJE 27. — Limrilm polyphemm. (After Kingsley.) Xiphosuia. 

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



Figure 28. — Limulus poh/phrmus. (After Packard, fiom Palfinir.) 

 Xi])hosura. Ventral view of embryo in the egg; showing the rudiments 

 of six pairs of legs ; ?«, mouth. 



VicvRK 20. —Lmmlus pnh/phemus. (After Packard, from Balfour.) 

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

 tary limlis on the ventral plate. 



The ligui'es of endjryonic fJmnlus are introduced foi- comjiarison. 

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

 necessary. 



