Amphignathodon, of which only one species is known, A. guentheri of Ecuador, agrees with Nototrema in all important characters except that it possesses teeth in the lower jaw in addition to those in the upper. There are further differences, but they are of degree only. The sacral diapophyses are more strongly dilated and the omosternum is absent. The tympanum is distinct. The pupil is horizontal; the roundish tongue is slightly free behind. The terminal phalanges are claw-shaped and carry large discs. The female has a dorsal pouch opening backwards. The skin of the head is involved in the ossification of the cranial bones. The skin of the back is smooth, slightly tubercular, non-granular below. The middle of the upper eyelid carries a small, pointed, cutaneous appendage, and even this little character occurs also in some species of Nototrema, e.g. in N. longipes and in N. cornutum. The heel carries a triangular little flap. The upper parts are olive in spirit-specimens, probably green in life; the borders of the dorsal pouch are black. The sides of the body are adorned with a black, white-edged streak, the limbs are whitish, with black cross-bars. The total length of the female type-specimen is 3 inches.
Sub-Fam. 2. Hylinae.–Lower jaw toothless.
The Hylinae are divided by Boulenger into 13 genera, which can be recognised by the following key, without reference to their natural affinities:–
A. The contracted pupil forms a horizontal slit.
a. Tips of the fingers and toes with large discs,
α. With vomerine teeth.
Female without a dorsal pouch .......... Hyla, p. [189].
Female with a dorsal pouch .......... Nototrema, p. [202].
β. Without vomerine teeth .......... Hylella, p. [203].
γ. With parasphenoid teeth and peculiar helmet-shaped head.