DEVELOPMENT AND METAMORPHOSIS. 



89 



front of them a small cleft, out of which the gill- 

 filaments of the branchial arches in process of dis- 

 appearance may often be seen projecting (Fig. 35). 



Pig. 35. 



Alytes obstetricans, towards the end of the larval stage, 

 showing the gills (br) protruding through the cleft in 

 front of the arm, and the median spiraculum (sp). 



Then only the caudal crests become reduced and the 

 tail gradually absorbed ; the gill-arches entirely dis- 

 appear ; the lungs, which had co-existed as accessory 

 respiratory and hydrostatic organs, assume alone (or, 

 rather, together with the skin) the respiratory func- 



FiG. 36. 



Development of Discoj'^osftis ^ji'cfas, x IJ. 



tions; the horny armature of the mouth and lips is 

 shed in pieces ; the lips are absorbed and the buccal 

 cleft extends ; the eyes become free and acquire move- 

 able lids ; the lachrymal canal is shifted towards the 



