Concerning the pairing and the other habits of the Anura of New South Wales we have some valuable notes by J. J. Fletcher.[[97]] He observes that Australian frogs spawn whenever they are ready, and when the very irregular conditions of moisture will allow it, but that they are not all ready at the same time, i.e. they have no fixed period of the year. Limnodynastes, Hyla aurea, and H. coerulea deposit their spawn in the water, in more or less irregular floating patches, which look white and frothy. The period extends from July to May, and is at its height in August and September; but if there is a spring-drought vigorous spawning may be looked for about the middle of January, when heavy showers are likely to occur. Crinia and several Hyla, e.g. H. ewingi, spawn at any time of the year. The eggs form small submerged bunches, enclosed in a transparent jelly, attached to the blades of grass or twigs of dead branches in the water.
Pseudophryne, a genus closely resembling Crinia, but on account of the absence of teeth in the lower jaw relegated to the Bufonidae, spawns during the Australian summer and autumn. The numerous ova of P. australis and P. bibroni are laid separately, not in the water, but under stones, or in the débris of reed- and grass-tussocks, on the edge of a pool.
The larvae of Pseudophryne and others have often to depend upon the next following rain, sometimes waiting for months to be released from the eggs, wherein they have so far developed. But the tadpoles, once hatched, probably do not bury themselves; they either metamorphose or die.
The males of Mixophyes and Hyla, grasp the females in the axillary region; those of Limnodynastes, Hyperolia, Crinia, and Pseudophryne throw their arms round the inguinal or lumbar region.
For some three months during the winter, commencing about May, the frogs, like lizards and snakes, resort to shelter under logs and stones, beneath which they are then to be met with in a more or less sleepy condition. During the hot and very dry periods many bury themselves in the drying-up mud, which becomes very hard, and does not release them until the next rains. They croak during showery times of the year. There is no evidence that any Australian species live in the high Eucalyptus-trees.
Hylopsis platycephalus, of South America, is of importance as forming a link with the Dendrophryniscinae, owing to the very small size of the teeth in the upper jaw. There are no vomerine teeth. The fingers and toes are webbed, and furnished with discs. The very small omosternum and the metasternum are cartilaginous. The pupil is horizontal. Total length, about or under 1½ inch.
Sub-Fam. 3. Dendrophryniscinae.–The two Neotropical genera of this sub-family are characterised by the entire absence of teeth. The toothless condition of the upper jaw is really the sole character which separates them from the Cystignathinae, taken as a whole. The suppression of the tympanum and of the Eustachian tubes in Batrachophrynus, and the fully webbed toes of B. macrostomus indicate complete adaptation to aquatic life. The absence of the omosternum in Dendrophryniscus, the absence of vomerine teeth, the dilated phalangeal tips, the entire and quite adherent tongue, are all features which likewise occur in some of the Cystignathinae, and therefore cannot be urged against their affinity. Lastly, the recently discovered South American genus Hylopsis is, as pointed out by Werner,[[98]] an intermediate link, owing to the extremely small, scarcely visible teeth in the upper jaw.
Dendrophryniscus brevipollicatus has been found in the neighbourhood of Rio Janeiro. The head is depressed and triangular. The tongue is entire, but free behind. The tympanum is suppressed. The omosternum is absent; the metasternum forms a long bony style. The sacral diapophyses are cylindrical. The terminal phalanges are simple, but carry dilated tips. The first finger is rudimentary. The skin is nearly smooth, reddish brown above, whitish below; the limbs are cross-barred.
Batrachophrynus inhabits the mountains of Peru. The head is much depressed and small, with the eyes directed upwards, as is usual in essentially aquatic species. The tongue is large, circular, and entirely adherent. The tympanum and the Eustachian tubes are suppressed. The omosternum is cartilaginous, and the metasternum forms a cartilaginous plate. The sacral diapophyses are cylindrical. The terminal phalanges are simple, and carry no discs. The four fingers are short; the toes are webbed. The male has no vocal sac. B. brachydactylus has a smooth skin, olive-brown above with darker spots. B. macrostomus, 2 inches in length, is distinguished by its larger size, and by its completely webbed toes.
Fam. 6. Engystomatidae (Narrow-mouthed Toads).–Firmisternia with dilated sacral diapophyses.