A Monograph on the Sub-class Cirripedia · Charles Darwin
PLATE 13.
_Genera_--PYRGOMA AND CREUSIA. Fig. 1 _a_, Pyrgoma grande; 1 _b_, scutum and tergum, calcified together, external view of; 1 _c_, scutum and tergum, internal view of; 1 _d_, the two scuta and terga, external view, seen from above, having their natural position, when closed. 2 _a_, Pyrgoma milleporæ, shell viewed from above; 2 _b_, internal view of, showing the sheath; 2 _c_, scutum and tergum, united, external view of; 2 _d_, scutum, _var._ external view of; 2 _e_, scutum, internal view of; 2 _f_, tergum, internal view of. 3 _a_, Pyrgoma dentatum shell, external view of; 3 _b_, scutum, _var._ 1, external view of; 3 _c_, tergum, _var._ 1, external view of; 3 _d_, tergum, _var._ 2, external view of; 3 _e_, scutum, _var._ 3, external view of; 3 _f_, tergum, _var._ 3, external view of; 3 _g_, scutum and tergum, _var._ 1, joined together, internal view of. 4 _a_, Pyrgoma crenatum, scutum, external view of, showing the great depending adductor plate and large occludent ledge; 4 _b_, external view of. 5 _a_, Pyrgoma monticulariæ, external view of; 5 _b_, another specimen, internal view of; 5 _c_, another specimen, external view of; 5 _d_, portion of circumference of shell, viewed externally, much magnified, showing the outer lamina, and the irregular, longitudinal septa; 5 _e_, another specimen of the same, with the longitudinal septa more regular; 5 _f_, scutum and tergum completely calcified together, external view of. 6 _a_, Creusia spinulosa, shell, seen from above. 6 _b_, 6 _c_, Creusia spinulosa, _var._ 1, scutum and tergum, internal view of; 6 _d_, scutum and tergum, joined together, external view of. 6 _e_, 6 _f_, 6 _g_, Creusia spinulosa, _var._ 2, 6 _e_, scutum, internal view; 6 _f_, tergum, internal view of; 6 _g_, tergum, of another specimen, internal view of. 6 _h_, Creusia spinulosa, _var._ 3, scutum and tergum joined together, external view of.
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