/. CRUSTACEA: CIRRIPEDIA. 



423 



The antennae, the first simple, the second frequently two- 

 branched, are used for swimming and creeping, and are bent back- 

 wards and provided with numerous joints and hairs. The 

 following appendages (mandible, maxillae, and three pairs of legs) 



FIG. 426. Cypris fa sciatus, adult female. (After Glaus.) I-IV, appendages; c, furca; 

 e, eye; /, liver; m, adductor muscle of shell; o, ovary; s, shell gland. 



vary greatly from genus to genus. The internal structure is also 

 variable. The Ostracoda are largely bottom forms and live in fresh 

 and brackish water as well as in the sea. 



CYPRIDINID^E. First two pairs of legs maxillary in character, the last 

 developed into a hook for cleansing the shell; heart v^esent; marine. 

 Cypridina* CYPRIDID.E. First pair of legs maxillary in character ; 

 heart lacking; fresh water. Cypris,* Candona.* 



Sub Class V. Cirripedia. 



The cirripeds, or barnacles, differ from all other Crustacea in 

 that they have lost their locomotor powers and live attached to 

 rocks, floating timber, and the like. In some cases they attach 

 themselves to other animals, as crabs and molluscs, or, as in the 

 case of Coronula, to whales. This leads 

 in Anelasma and the Rhizocephala to a 

 true parasitism, the barnacle not only 

 attaching itself to an animal but sucking 

 its juices as food. 



The attachment is by the dorsal sur- 

 face in the neighborhood of the head, 

 and is initiated by the first antennae, in 



which is a cement gland secreting a no. 427.-flaZajitw/iameri,* acorn 

 rapidly hardening cement. The region Dan e )' Formed of rosteum' 



nf fivatirm in +Vio "RalQnirJco (Grr /fO^N lateralia, and carina, the 



nxation in tne tfaiamdae (fig. 4xJ7) opercuium of scuta () and 

 lies in the plane of the head; in the terga (t) - 

 Lepadidae it is drawn out into a long muscular stalk (fig. 114). 

 To this attached life are related all the peculiarities of structure. 



