/. CRUSTACEA: CIRRIPEDIA, LEPADID^S, BALANID^E. 



roditic species, hermaphroditic species with complemental males, 

 and purely dioecious species. 



Since the hard shells of the barnacles resemble those of the molluscs, it 

 is not to be wondered that these forms were long regarded as belonging to 

 that group. It was not until the development (fig. 429) was studied that 



oe 



FIG. 429. Nauplius (A) and Cypris (B) stages of Sacculina carcini. (After Delage.) 

 1, 2, antennae ; 5, mandible ; /, cirrhous foot ; m, muscles ; oc, nauplius eye ; ou, 

 anlage of ovary. 



the error was corrected. A large nauplius comes from the egg and later 

 is metamorphosed into a second larval stage with bivalve shell which, 

 from its appearance, is called the cypris-stage. This becomes fixed and 

 develops into the adult, losing the compound eyes and retaining the nau- 

 plius eye. 



Order I. Lepadidae. 



Stalked cirripeds, with shell largely formed of scuta, terga, and carina ; 

 other parts may be added. Lepas anatifera* 

 (fig. 114) is the goose barnacle, which owes 

 its common name to a mediaeval myth 

 which claimed that the Irish (or bernicle) 

 goose developed from these animals. L. 

 fascicularis,*(tig. 430), abundant floating on 

 the eastern coast. Anelasma squalicola, a 

 thin-skinned barnacle, is parasitic on sharks 

 and forms a transition to the Rhizocephala. 

 Order II. Balanidae. 



Sessile cirripeds with calcareous shell 

 formed of carina, rostrum, and lateralia; 

 scuta and terga forming the valves (fig. 427). 

 Balanus ~balanoides* common on our coast. 



Coronula dwdemata, attached to the skin FlG 

 of whales. 



fascicularis,* 

 goose barnacle. (From Smith.) 



