stage with the slimy mucus which surrounds them.  Nature always discovers such cunning schemes to get over apparent difficulties in her way:  and the tree-frogs have solved the problem for themselves in half a dozen manners in different localities.  Oddest of all, perhaps, is the dodge invented by “Darwin’s frog,” a Chilean species, in which the male swallows the eggs as soon as laid, and gulps them into the throat-pouch beneath his capacious neck:  there they hatch out and pass through their tadpole stage:  and when at last they arrive at frogly maturity, they escape into the world through the mouth of their father.

[Illustration:  NO. 8.  THE SURINAM TOAD.]

The Surinam toad, represented in No. 8, is also the possessor of one of the strangest nurseries known to science.  It lives in the dense tropical forests of Guiana and Brazil, and is a true water-haunter.  But at the breeding season the female undergoes a curious change of integument.  The skin on her back grows pulpy, soft, and jelly-like.  She lays her eggs in the water:  but as soon as she has laid them, her lord and master plasters them on to her impressionable back with his feet, so as to secure them from all assaults of enemies.  Every egg is pressed separately into a bed of the soft skin, which soon closes over it automatically, thus burying each in a little cell or niche, where it undergoes its further development.  The tadpoles pass through their larval stage within the cell, and then hop out, in the four-legged condition.  As soon as they have gone off to shift for themselves, the mother toad finds herself with a ragged and honeycombed skin, which must be very uncomfortable.  So she rubs the remnant of it off against stones or the bark of trees, and re-develops a similar back afresh at the next breeding season.

Almost never do we find a device in nature which occurs once only.  The unique hardly exists:  nature is a great copyist.  At least two animals of wholly unlike kinds are all but sure to hit independently upon the self-same mechanism.  So it is not surprising to learn that a cat-fish has invented an exactly similar mode of carrying its young to that adopted by the Surinam toad:  only, here it is on the under surface, not the upper one, that the spawn is plastered.  The eggs of this cat-fish, whose scientific name is Aspredo, are pressed into the skin below the body, and so borne about by the mother till they hatch.  This is the second instance of which I spoke above, where the female fish herself assumes the care of her offspring, instead of leaving it entirely to her excellent partner.