I40 THE CRUSTACEA 



Sub-Class Cirripedia. 



Order 1. Thoracica, 



A mantle pre^^eiit. Six pairs of ciriifonn tiinik-a])pendages. 



Sub-Order 1. Pedunculata. 



Peduncle and capitulum distinct. Onter jilates of shell, wlien present, 

 not forming a "wall." 



Family Lepadidae. Lepas, Linn. (Fig. 57, A) ; Dichelasjns, Darwin ; 

 Pollicipes, Leach (Fig. 60); Scalpellmn, Leach (Fig. 61); Ibla, Leach (Fig. 

 71) ; Lithotrya, Sowerby ; ConchoJerma, Olfers ; Alcpas, Rang ; Anclasma, 

 Darwin (Fig. 68) ; Koleoh'pas, Stebbing. 



Sub-Order 2. Operculata. 



No peduncle. Scuta and terga forming a movaljle operculum. Outer 

 plates of shell coalesced to form a " wall." 



Tribe \. Asymmetrica. 



Scutum and tergum of one side movable, without depressor muscles. 

 Family A^errucidae. Verruca ^ Schum. 



Tribe 1. Symmetrica. 



Scuta and terga of both sides movable, with dejjressor muscles. 



Family Balanidae. Balanns, Lister (Fig. 57, B) ; Coronula, 

 Lamarck ; Tuhicinella, Lamarck ; Xenohalanus^ Steenstrup (Fig. 65) ; 

 Elminius, Leach ; Pyrogovia, Leach. Family Chthamalidae. Chtha- 

 maliis, Ranzani ; Catophragmus, So\\erl)y (Fig. 62) ; Octomeris, Sowerby. 



Order 2. Acrothoracica. 



A mantle present. Trunk-appendages reduced in inuuber, the 

 posterior paiis widely separated from the first pair. 



Family Alcippidae. Alrippe, Hancock {Trypefesa, Norman) (Fig. 72). 

 Family Kochlorinidae. Kachlorine, Noll. Family Cryptophialidae. 

 Cryptopliialus, Darwin. 



Order 3. Ascothoracica. 



Mantle containing diverticula of alimentary canal. Triuik-ap2:)end- 

 ages more or less reduced. 



Family Lauridae. Laura, Lacaze-Duthiers (Fig. 76. Family 

 Synagogidae. Synagoga, Norman. Family Petrarcidae. Pcfrarca, 

 Fowler. Familv Dendrogastridae. Dcndrogasfer, Knijiowitsch (Fig. 

 78). 



Order 4. Apoda. 



Mantle absent. No trunk-ap])endages. 



Family Proteolepadidae. Proteolepas, Darwin (Fig. 79). 



