REPRODUCTIVE SYSTEM. 515 
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 wvigarous. But all 
the three terms are bad. 
