Concerning the evolution of the classification of the Anura, it is interesting to follow the changes of the value attached to the various anatomical characters by systematists. At first the presence or absence of teeth and of adhesive discs on the fingers and toes were considered to be of prime importance for the division of the Phaneroglossa.
Duméril et Bibron, 1841. "Erpétologie générale."
II. Phrynaglosses = Aglossa of Wagler: Pipa and Xenopus.
II. Phanéroglosses. 1. With teeth. a. Without discs: Raniformes.
II. Phanéroglosses. 1. With teeth. b. With discs:out Hylaeformes.
II. Phanéroglosses. 2. Toothless. Bufoniformes.
Stannius, 1856 (see p. [8]), separated the Engystomatidae as "Systomata," and used the presence or absence of the "manubrium sterni" (omosternum) as a character of distinction between his Bufoninae and Raninae.
Günther, 1858, "Catalogue of the Batrachia Salientia." No progress was made by his scheme, which relied upon the tongue and digits.
Aglossa with Myobatrachus.
Opisthoglossa. a. Oxydactyla. b. Platydactyla.