VIII 



DEVELOPMENTAL ADAPTATIONS 



461 



medusa ikeringii (von Ihering, 1886), Hyla nebulosa (Goeldi, 1895), 

 Rhac.ophoru* reinwardtii (Siedlecki, 1909). In the last mentioned 

 the eg.us an- deposited in a mass of foam mrlusud in one or several 

 leaves (Fig. 210). At the appropriate time the central portion of 

 the mass liquefies and the colourless tadpoles make their way into 

 this (vnlral fluid the superficial layer of the mass being hard 

 and dry. Eventually the lower part of the mass softens and the 

 liquid (nntaining the tadpoles trickles out on to the ground where 

 the larvae are able to continue their development in the smallest 

 puddles. 



In the second type of such adaptations the eggs or young are 

 carried about, away from the water, by 

 one of the parents. In the simplest of 

 such cases no structural modification of 

 the parent's body is involved. Thus in 

 Alytes obstetricans the male draws the 

 strings of eggs out of the cloacal aperture 

 of the female and loops them round his 

 thighs the portion of oviducal secretion 

 lying between successive eggs becoming 

 highly elastic and gripping the thighs 

 tightly. Oviposition takes place on land 

 and the male pays only occasional'visits 

 to the water. When one of these happens 

 at the appropriate period the young hatch 

 in the form of tadpoles while the male 

 parent resumes his terrestrial habits. 



In a number of cases the transport 

 of the young by the parent takes place 

 at a later period, when the tadpole stage 

 has been reached, the larvae adhering bo 

 the back of the male parent and so being 

 transported from one 'pool to another 

 (Fig. 211, A). This habit occurs in 

 various species of Dendrobates and Phyllo- 

 bates (Brandes u. Schoenichen, 1901). 



In the most interesting cases however 

 the transport of the eggs or young by the 

 parent is associated with the making use 



of some particular structural feature of the latter either permanent 

 or specially developed for this purpose. In Rhacopliorus reticulatus 

 (Giinther, 1876) the eggs are carried about by the female, adherent 

 to its ventral surface. In Hyla goeldii (Boulenger, 1895) the eggs 

 adhere to the dorsal surface of the female, only in this case the skin 

 of the parent responds to the stimulus afforded by the presence of 

 the eggs and grows up into a slight ledge surrounding them (Fig. 

 211, B). In Pipa americana (Bartlett, 1896) the cloaca of the 

 female is protruded at the time of Oviposition as a large spout-like 



FlG. 210. Rhai-nftlion's 



wardtii, mass of spawn with 

 hatched tadpoles. (After Sied- 

 lecki, 1909.) 



