Lophobranchii \Loph`o*bran"chi*i\, n. pl. [NL., fr. Gr. lo`fos a crest or tuft + bra`gchion gill.] (Zool.) An order of teleostean fishes, having the gills arranged in tufts on the branchial arches, as the Hippocampus and pipefishes. [1913 Webster]