Correct Answer - D
(i) Procoelus (Pro=front, coelus=cavity): Centrum is concave anterorely.
e.g.:-Typical vertebrae of frog (2 to 7) -vertebrate of snakes and lizards.
(ii) Amphicoelous(Amphi=both):Centrum is concave at both sides.
e.g.:-8th vertebra of frog-Vertebrate of most fishes.
(iii) Acolous or Amphiplatyan(Platy=flat):Centrum flat at both ends, without a concavity,
e.g.-9th vertebra of frog- Vertebrae of mammals.
(iv) Heterocoelous (hetro=asymmetrical):-The centrum is like a saddle.
e.g.:-Vertebae of birds.
