With regard to the specific characters of the species of Zeugopterus nothing is known of peculiarities in mode of life which would give an importance in the struggle for existence to the Concrescence of the pelvic fins with the ventral in punctatus, to the absence of this character and the elongation of the first dorsal ray in unimaculatus, or to the absence of both characters in norvegicus.
"Hormones and Heredity"
J. T. Cunningham