Chap. IX. CIREIPEDIA AND EHIZOCEPHALA. 89 



In these also the brood bursts out in the Nauplius- 

 form, and speedily strips off its earliest larva- skin which 

 is distinguished by no peculiarities worth noticing. Here 

 also we find again the same pyriform shape of the un- 

 segmented body, the same number and structure of the 

 feet, the same position of the median eye (which, how- 

 ever, is wanting in Sacculina purpurea, and according 

 to Darwin in some species of Lepas), and the same 

 position of the "buccal hood," as in the Nauplii of the 

 Prawns and Copepoda. From the latter the Nauplii of 

 the Cirripedia and Khizocephala are distinguished by 

 the possession of a dorsal shield or carapace, which 

 sometimes {Sacculina purpurea) projects far beyond the 

 body all round ; and they are distinguished not only 

 from other Nauplii, but as far as I know from all other 

 Crustacea, by the circumstance that structures which 

 are elsewhere combined with the two anterior limbs 

 (antennae), here occur separated from them. 



The anterior antennae of the Copepoda, Cladocera, 

 Phyllopoda (Leydig, Claus), Ostracoda (at least the 

 Cypridinae), Diastylidae, Edriophthalma, and Podoph- 

 thalma, with few exceptions relating to terrestrial ani- 

 mals or parasites, bear peculiar filaments which I have 

 already repeatedly mentioned as " olfactory filaments." 



combine the Ehizocephala with the Cirripedia, as Liljeborg has done, 

 but place them in opposition as equivalent, like the Amphipoda and 

 Isopoda. The near relationship of the Cirripedia to the Ostracoda is 

 also spoken of, but the similarity of the so-called " Cypris-like larvse," 

 or Cirriped-pupsB as Darwin calls them, to Cypris is so purely external, 

 even as regards the shell, that the relationship appears to me to be 

 scarcely greater than that of Peltogaster socialis (fig. 59) with the 

 family of the sausages. 



