Five specimens have round subarticular tubercles beneath the fourth fingers; six specimens have a bifid tubercle on one hand, and two specimens have bifid tubercles on both hands.
"A Review of the Middle American Tree Frogs of the Genus Ptychohyla"
William E. Duellman
Many individuals have a bifid subarticular tubercle beneath the fourth finger.
"A Review of the Middle American Tree Frogs of the Genus Ptychohyla"
William E. Duellman
Thus if the experiments give a cross-over value of 5 per cent for white and bifid, we say that white and bifid lie 5 units apart in the X chromosome.
"Sex-linked Inheritance in Drosophila"
Thomas Hunt Morgan Calvin B. Bridges