A treatise on zoology . numbers on . the dermal skeleton of the Siluroids,where they are movably articulated to the underlying bones (). This puzzling fact can at present only be accounted for on thesupposition that the Siluroidei have been derived from ancestralTeleosts in which the dermal denticles were still present, as theyare in Poljipterns and Lepidosteiis. The Teleostean scale develops like the ganoid (Hofer [215^?],.Klaatsch [264], Ussow [471], Hase [198]). Mesoblastic cells gathertogether below the basement membrane, forming papillae whichproject slightly into the epidermis. In
A treatise on zoology . numbers on . the dermal skeleton of the Siluroids,where they are movably articulated to the underlying bones (). This puzzling fact can at present only be accounted for on thesupposition that the Siluroidei have been derived from ancestralTeleosts in which the dermal denticles were still present, as theyare in Poljipterns and Lepidosteiis. The Teleostean scale develops like the ganoid (Hofer [215^?],.Klaatsch [264], Ussow [471], Hase [198]). Mesoblastic cells gathertogether below the basement membrane, forming papillae whichproject slightly into the epidermis. In the middle of each mass-of scleroblasts as it spreads out appears a thin lamella of skeletalsubstance (Fig. 343, A). This increases in size and thickness by theaddition of new layers, the scleroblasts covering its entire surrounding tissue becomes the loose packet in which theadult scale is lodged (Fig. 193). The front edge of the scalegrows inwards; the hinder edge outwards, carrying the epidermiswith ctenoid scale of Eiythrichthys nitidus, Ricli.(After Gunther.) PHOSPHORESCENT ORGANS 357 Deep-sea Teleostean fish are variously modified in adaptation totheir peculiar environment, and among the most characteristicstructures developed in them are the phosphorescent differ considerably in the various genera and in thedifferent parts of the same animal. The more elaborate phos-
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
