ClipArt ETC
"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…