Each of the four fingers ends in a four-armed star, the tips of which again carry four or five sensory papillae. The cartilage of the terminal phalanges is correspondingly star-shaped.
According to Klinckowstroem these toads, which are entirely aquatic, are easily collected at the end of the long dry period, when they are all confined to the half-dried-up pools. But they do not spawn there. This happens after the rains have inundated the forest, and then it is very difficult to get the females with eggs on their backs. Each of the eggs, when once they have been glued on to the back, sinks into an invagination of the skin. The initial stages are probably the same as those caused by the eggs on the belly of Rhacophorus reticulatus (see p. [248]). Later, each egg is quite concealed in a cavity with a lid. These cavities are simply pouches of the skin, and are not formed by enlarged glands as has been suggested by some anatomists. Each cavity consists of the epidermal pouch and the lid. How the latter is produced is not known. According to the authors quoted above, the lid looks like a shiny or sticky layer which has hardened into horn-like consistency. It lies exactly like a lid upon the rim of the pouch itself, and is certainly not in structural or organic continuity with the epidermis. Most probably it is produced by the remnant of the egg-shell itself, which, after the larva is hatched, is cast up to and remains on the top of the cup.
Bartlett[[76]] has described the spawning of specimens in the Zoological Gardens in London.
"About the 28th of April 1896 the males became very lively, and were constantly heard uttering their most remarkable metallic, ticking call-notes. On examination we then observed two of the males clasping tightly round the lower part of the bodies of the females, the hind parts of the males extending beyond those of the females. On the following morning the keeper arrived in time to witness the mode in which the eggs were deposited. The oviduct of the female protruded from her body more than an inch in length, and the bladder-like protrusion being retroverted, passed under the belly of the male on to her own back. The male appeared to press tightly upon this protruded bag and to squeeze it from side to side, apparently pressing the eggs forward one by one on to the back of the female. By this movement the eggs were spread with nearly uniform smoothness over the whole surface of the back of the female to which they became firmly adherent. On the operation being completed, the males left their places on the females, and the enlarged and projected oviduct gradually disappeared from one of the females. In the other specimen, the oviduct appears not to have discharged the whole of the eggs."
Boulenger, who examined this second specimen, which died, confirmed this egg-bound condition. He remarks further: "The ovipositor formed by the cloaca (not by the prolapsed uterus), was still protruding and much inflamed. It may be deduced from the observation made by the keeper, that fecundation must take place before the extrusion of the eggs, and it is probable that the ovipositor serves in the first instance to collect the spermatozoa which would penetrate into the oviducts, the eggs being laid in the impregnated condition, as in tailed Batrachians."
Sub-Order 2. Phaneroglossa–Fam. 1. Discoglossidae.–The tongue has the shape of a round disc, adherent by nearly the whole of its base, and it cannot be protruded. The vertebrae are opisthocoelous, and in the aquatic genera are of the most exaggerated epichordal type; the diapophyses of the second to the fourth vertebrae carry short, free ribs, and those of the sacral vertebra are dilated. The metasternum behind is forked. The upper jaw and the vomers are provided with teeth. The males have no vocal sac. The tadpoles are distinguished by having the opercular spiracle placed in the middle of the thoracic region (see general anatomical part, p. [44]).
The few members of this family have a peculiar distribution. Liopelma is confined to New Zealand, where it is the solitary representative of the Amphibia. Ascaphus is found in North America. The other genera, Discoglossus, Bombinator, and Alytes, are typical of the Palaearctic sub-region, and are, with the exception of Bombinator, confined to the Western Provinces (cf. Map, Fig. 32, on p. [161]).
Discoglossus.–The tympanum is frequently more or less concealed by the skin. The pupil is round or triangular. The omosternum is small. The vertebrae are of the epichordal type.
D. pictus, the only species, has a smooth and shiny skin, provided with numerous small mucous glands. The palms of the hands are provided with three tubercles, of which the innermost is the largest, and is carried by the vestige of the thumb. The coloration of this species is very variable. The ground-colour of the upper parts is a rich olive brown with darker, light-edged patches, which are either separate or confluent in various ways, forming broad, longitudinal bands, or a few larger asymmetrical patches, separated in some individuals by a broad and conspicuous light brown or yellowish vertebral stripe. An irregular reddish band frequently extends from the eyes backwards along the sides. The under parts are mostly yellowish white. This variability is purely individual, the most differently marked and variously coloured specimens being found in the same locality and even amongst the members of one and the same brood. The male develops various nuptial excrescences, consisting of minute, dark, horny spines, notably on the inner palmar pad, on the inner side of the first and second finger, on the chin and throat, and smaller and more scattered spicules on the belly and legs.
This pretty and extremely active little creature, which measures between 2 and 3 inches in length, is confined to the south-western corner of the Palaearctic sub-region, being found in Algiers and Morocco, Sicily, Sardinia, Corsica, and the southern and western parts of the Iberian Peninsula. Curiously enough it is absent in the Balearic Isles. Rather aquatic in its habits, frequenting pools and streams, it is also often found on land.