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SYSTEMATIC ZOOLOGY 



FlG. 150. Balanus, an incrusting barnacle. A, lateral external aspect; B, anatomy. 

 a, antennules; <n/, adductor muscle; m, muscles of scuta and terga ; o, edge of parapet; 

 ov, ovary; ovi, oviduct ; s, scutum ; sk, parapet; /, tergum ; wo, female aperture. (After 

 Darwin, from Parker and Haswell's Text-book.) 



FlG. 151. Sacculini carcim, a parasitic barnacle on abdomen of a crab, br, branchial 

 region of crab; /, hepatic region ; 1/, intestinal region ; ks, body of parasite; />. pedum 

 mfi, basilar membrane, giving off rootlike processes which extend throughout the body of 

 the host. (After Delage, from Parker and Haswell's Text-book.) 



