But again surprises await us. Many frogs and toads, both the mothers and the fathers, show a really marked development of the familial instincts.[18] An illustration of this care is furnished by a large tree-frog (_Hyla faber_) of Brazil, commonly known as the _Ferreiro_, “the smith,” from its strange voice resembling the mallet of a smith, slowly and regularly striking on a metal plate. This frog prepares a nursery in the shallow waters of the ponds, where a basin-shaped hollow is dug in the mud. The building is done by the mother, the material removed being used to form a wall, circular in shape, which is carried up to the surface of the water. In this cavity the eggs are placed, protected against the attacks of aquatic insects and fishes. A Japanese tree frog (_Rhacophorus schlegelii_) builds a similar nest, but here the mother lines the walls of her nursery with a secretion, a kind of milk food, from her own body, which by rapid movements of her feet is worked into a froth, and in the midst of this foamy mass the eggs are laid. More remarkable is the nursery building of the “Wollunnkukk” frog (_Phyllomedusa hypochondrialis_) of Paraguay, whose habits were noted by Dr. Budgett during the exploration of the Paraguayan Chaco. “Whilst sitting near the water’s edge he saw a female carrying a male upon her back. At last she climbed up the stem of a plant, reached out and caught hold of an overhanging leaf and climbed on to it. Both then caught hold of its edges and held them together; and into the funnel thus formed the female poured her eggs, the male fertilising them as they passed. The jelly surrounding the eggs served as a cement to hold the edges of the leaves together. Then, moving up a little further, the process was repeated until the leaf was full, and about a hundred eggs had been enclosed.”[19] A similar leaf nest is made by a Brazilian frog, known as Ihering’s frog (_P. Iheringí_), while a home of more elaborate construction, in which several leaves are used, is prepared by Savage’s leaf-frog (_P. Sauvagii_). It should be noted that in these cases the care of the parents is confined to the providing of a nursery; when once this is done the young are abandoned. But many frogs and toads do much more than this, and one or other parents, most often the father, guard their offspring with jealous care. A Papuan frog-father, for instance, takes up the duties of a nurse; and when the eggs are laid, he sits upon them, holding the mass with both hands. And this vigil he keeps during the whole time while the young are undergoing growth, passing through the larval and tadpole stage.