. The Cambridge natural history. Zoology. PEDUNCULATA—-OPERCULATA 89 which they live ; they exhibit a degenerate structure, but still retain two pairs of cirri. The large individuals of /. quadrivalvis, on the other hand, are hermaphrodites, but they harbour witliin their mantles minute complemental males similar to those of /. cumiiigii, though tliey are rather larger. Fam. 4. Anaspidae.—This includes the remaining pedun- culate genera, characterised l)y the fleshy nature of the mantle and peduncle, which are both entirely devoid of cal- cifications. The species of Alcpas live upon Echinoderm
. The Cambridge natural history. Zoology. PEDUNCULATA—-OPERCULATA 89 which they live ; they exhibit a degenerate structure, but still retain two pairs of cirri. The large individuals of /. quadrivalvis, on the other hand, are hermaphrodites, but they harbour witliin their mantles minute complemental males similar to those of /. cumiiigii, though tliey are rather larger. Fam. 4. Anaspidae.—This includes the remaining pedun- culate genera, characterised l)y the fleshy nature of the mantle and peduncle, which are both entirely devoid of cal- cifications. The species of Alcpas live upon Echinoderms and various other animals ; Chaetolepas upon Sertularia, and Gymnolepas upon Medusae. Anelasma sqiudicola is an interesting form, living parasitically upon the Elasmobranch fishes, Selache maxima and Spinax niger in the North Sea. The peduncle is deeply buried in the flesh of the host, so that only a portion of the dark blue capitulum protrudes to the surface. From the whole surface of the peduncle a system of branching processes is given off, which ramify far into the tissues of the fish, and communicate inside the peduncle with the lacunar tissue, whicli is packed round all the organs of the Cirripede. There can be small doubt that the Anelasma derives its nutriment parasitically through tliis root-system, since the cirri are mere fleshy lobes un- adapted to securing food, and the alimentary canal is always empty. This animal has a sug- gestive bearing on the IJhizo- cephala, which, as will be shown, derive their nutriment from a system of roots iK'nelrating the host and growing out from what corresponds morphologically to tlie Sub-Order 2. Operculata, The " acorn-l)arnacles " appear later in y-eoloffical time tlian the earlier stalked forms, ^'crrura and Clitliamalua are found in the Chalk, and survive down to the present day, but Ikdanus does not occur until middle Tertiary times. Eepresentalives of the last-named genus are familiar to every one,
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Keywords: ., bookauthorsh, bookcentury1800, bookdecade1890, booksubjectzoology
