LIMITATION IN LOWER VERTEBRATES 141 



tiny pond, smoothing it with her hands on the inside and continuing 

 her labours until the edge is raised above the surface of the water. 

 The spawn is deposited in this little nest and the parents lurk near 

 it for some days, but appear to take no special precautions for 

 guarding the young. In other 

 cases the eggs are laid out 

 of the water, in holes or under 

 grass, so that they are saved 

 from aquatic enemies in their 

 early stages, and the tadpoles 

 are washed into the water by 

 rain after they have emerged 

 from the egg. Phyllomedusa 

 iheringi, a Brazilian frog, also 

 deposits her eggs out of water. 

 A male and female leave the 

 water together, climbing up 

 on flat leaves, one of which 

 the two animals hold twisted 

 to a funnel. The female de- 

 posits a mass of eggs in this, 

 and their sticky surface ad- 

 heres to the leaf, leaving it 

 folded round the mass. After 

 the formation of this simple 

 nest, there is no further pro- 

 vision for the young, and the 

 tadpoles, when they emerge, 

 have to wriggle down into 

 the water. The male of the 

 midwife toad (Alytes obstetri- 

 cans), a common batrachian 

 in Europe, winds a string of 

 eggs round his hind-legs, im- 

 mediately after they have been laid, and then retreats to a hole. 

 At night he comes out to feed, and at the same time moistens 

 the eggs, sometimes carrying them down to water and dipping 

 them in it. After three weeks of nursing them in this careful 

 way, the male carries them, now ready to hatch, down to the 

 water, where the tadpoles emerge, and his responsibility ends. 

 In Rhinoderma darwini (Fig. 29), a small frog discovered by Darwin 



FIG. 29. Darwin's Rhinoderma, showing 

 Brood-pouch. The frog has been dis- 

 sected from the ventral side ; the skin on 

 the right has been cut away, showing the 

 opening from the mouth to the pouch, 

 the posterior half of which has been 

 opened to show the young frogs. (After 

 HOWES; enlarged.) 



