BATBAOHIANS. 



177 



producing a greater volume of sound swell out on each side 

 of the head of the males. Among the few viviparous Bi- 

 ti-acliians known is an Alpine European salamander 

 {S. atra) which brings forth its young alive. 

 Unlike young fishes, the yolk is entirely absorbed before 



Fig. S94. — ji:toloil, or larval Salamander, showing the ^lls. heart (H), aortic 

 branches and lungs {FA). P, pulmonary arteries; pp. pulmonary veins; A, 

 bulbus arteriosus, from which the vascular arches {B) originate; 'j6, bran- 

 chial vein; the lower A, vena cava; V, descending aorta. 



the tadpole leaves the egg. In warm climates the tadpoles 

 hatch in four or five days after the eggs are laid. When 

 hatched the tadpole is not so well developed as in most 

 young fishes. The digestive canal at first is simple and 

 straight. Afterwards it becomes remarkably long, and 



