42 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



Fig. 16. — Cirripedia: Rhizocephala. Metamorphosis of Sacculina carci>ii Thomp- 

 son (from Delage, 1884). 



A, nauplius. B, free-swimming cjpris stage ready to moult. C, cypris fixed 

 by antenna at base of hair of crab, shell separated, thorax detached and thrown 

 of? with internal tissues. D, larva still in shell has formed a new cuticle (iCt). 

 E, shell being shed, larval body retracted witliin cuticle, with long, hollow "dart" 

 (d) extended toward base of antenna. F, larva with a second inner cuticle 

 i^Ct), the dart extended into antenna. G, larval body expanded, the dart has 

 pierced the hair membrane of the crab. 



Ab, abdomen; lAnt, first antenna; iCt, outer cuticle; ^Ct, inner cuticle; d, 

 dart ; fh, frontal horn ; Hr, hair of crab ; Sh, cypris shell ; Th, thorax. 



