To these succeeded forms where the down had developed into body feathers for warmth, not flight, whilst the fore-limbs had become organs of prehension, the hind-limbs of progression.
Very often one or other of the appendages may be modified for prehension, the seizing of prey or the holding of a mate.
In a few Ostracoda, by a rare exception, the masticatory process is reduced or suppressed, and the palp alone remains, forming a pediform appendage used in locomotion as well as in the prehension of food.
The folds are so disposed that the thick skin shall be capable of bending in grasping, while at the same time it requires to be tightly bound down to the skeleton of the hand, else the slipping of the skin would lead to insecurity of prehension, as the quilting or buttoning down of the covers of furniture by upholsterers keeps them from slipping.
It is covered with numerous large papillae, and forms, like the trunk of the elephant, an admirable organ for the examination and prehension of food.