468 STRUCTURE OF VERTEBRATA. 



parous is applied. In some sharks, a few Teleosteans, some 

 tailed Amphibians, a few lizards and snakes, the young are 

 hatched before they leave the body of the mother. To 

 these cases the awkward term ovo-viviparous is applied, but 

 there is no real distinction between this mode of birth and 

 that called oviparous, and both may occur in one animal 

 (e.g. in the grass-snake) in different conditions. In the 

 placental Mammals there is a close organic connection 

 between the unborn young and the mother, and the 

 parturition in this case is usually called viviparous. But all 

 the three terms are bad. 



