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"The arrangement shown in fig. 22, where a, a, a, a, are four barbs in transverse section, viewed from the cut surfaces, with their anterior, b, b, b, b, and posterior, c, c, c, c, barbules, the former bearing the hooklets which catch over the edge of the latter." Elliot Coues, 1884

Barbs

"The arrangement shown in fig. 22, where a, a, a, a, are four barbs in transverse section, viewed from…

"Fig. 21. -A single barbule, baring barbicels and hooklets; magnified; after Nitzsch. ...barbicels (another dimin. of barba), also called cilia, or lashes (fig. 21); and hamuli, or hooklets (Lat. hamulus, a little hook; fig 21). These are simply a sort of fringe to the barbules, just as if the lower edge of the barbules were frayed out, and only differ from each other in that barbicels are plain hair like processes, while hamuli are hooked at the end; they are not found on all feathers, nor on all parts of some feathers." Elliot Coues, 1884

Single Barbule

"Fig. 21. -A single barbule, baring barbicels and hooklets; magnified; after Nitzsch. ...barbicels (another…

"Parts of a feather. I., Four barbs (B.) bearing anterior barbules (A.BB.) and posterior barbules (P.BB.); II., six barbs (B.) in section, showing interlocking of barbules; III., anterior barbule with barbicels (H.)." -Thomson, 1916

Feather Parts

"Parts of a feather. I., Four barbs (B.) bearing anterior barbules (A.BB.) and posterior barbules (P.BB.);…

"Fig. - 20 - Two barbs, a, a, of a vane, bearing anterior, b, b, and posterior, c, barbules; enlarged; after Nitzsch." Elliot Coues, 1884

Structure of a Feather

"Fig. - 20 - Two barbs, a, a, of a vane, bearing anterior, b, b, and posterior, c, barbules; enlarged;…

"Respiratory system of hag, from ventral surface. b., Barbules; m., mouth opening on ventral surface; g., gullet; g.p'., first gill-pouch, cut open to show internal lamellae; g.p.6, sixth gill-pouch; v., ventricle of heart; ao., aorta; a., common exhalant aperture." -Thomson, 1916

Hagfish Respiratory System

"Respiratory system of hag, from ventral surface. b., Barbules; m., mouth opening on ventral surface;…