. Outlines of zoology. ^?^ 362 PHYLUM ARTHROPODA. mostly generalised types, prophetic of rather than referableto the modern orders. As to the pedigree of insects, the wingless Collembolaand Thysanura are doubtless primitive. In Protopteron,for instance, there are appendages on the first four seg-ments of the abdomen, and the genital apertures are , Acerentomon is a little blind creature, withoutantennae, without cerci, without stigmata, with suctorialmouth-parts, with eleven abdominal segments, with apeculiar anal segment, with an unpaired genital aperture

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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology