loopback packet processing.

Hi all,
       I want to know that when i send a packet on loopback on
127.0.0.1 the packet is given to netif_rx without MAC header adding. I
want to know Is that correct? If yes then what happen to that 14 byte
MAC header bytes space in case Ping packet? Is that space free? Why
eth_type_trans is called that checks eth->h_proto field ?
     Please correct me if i am wrong.
Thanks in advance,
harsh.