REPRODUCTION 201 



folding a leaf with her hind limbs, so as to afford some pro- 

 tection to the egg. The eggs of these Batrachians are quite 

 small and soon become converted into the whole embryo. 

 The development is not very unlike that of ordinary frogs, 

 but the tadpole stage, characterised by a swollen body, a 

 mouth armed with a horny beak and surrounded with lips 

 beset with horny teeth, internal gills enclosed in a diverticu- 

 lum of the skin, in which the fore limbs grow without being 

 visible externally, does not exist. The body in most larval 

 forms does not differ much from that of the adult, three pairs 

 of branched, fringed, or tufted external gills are present, the 

 jaws and the palate are beset with teeth, differing in their 

 disposition from the final dentition, and the fore limbs grow 

 before the hind pair. (Fig. 17.) 



But other forms afford better protection to their offspring, 

 which are not abandoned to themselves until they have 

 reached a much more advanced condition, either by being 

 retained in the body of the mother, or by being provided with 

 a much greater amount of food-supply within the egg, which 

 again may be guarded by one of the parents or sheltered in a 

 nest. These interesting cases, most of which have only come 

 to light within the last few years, are here arranged in a 

 similar order to that adopted when dealing with the Tailless 

 Batrachians. 



(1) Protection by means of nests or nurseries. 



A. In holes on land or in trees. 



B. In a transparent bag in the water. 



(2) Direct nursing by the parent. 



A. The mother coils herself round the eggs. 



B. The father coils himself round the eggs. 



C. The mother carries the eggs on her back or round 



the body. 



D. Eggs retained in the oviducts (viviparity). 



(1) A. The species of Autodax,a genus of Californian sala- 

 manders of terrestrial and nocturnal habits, lay their twelve to 

 twenty eggs in a dry hole in the ground or, more frequently, 

 in a hole in a tree, up to thirty feet above the ground. The 

 mother, or both parents, remain in the hole during the develop- 

 ment, the object being probably to maintain the eggs in the 

 high degree of moisture essential to their development, and 



