pygopod

from The Century Dictionary.

• In ornithology, rump-footed, as an auk, loon, or grebe; having the legs inserted far back, appearing close by the rump; of or pertaining to the Pygopodes.
• In herpetology, of or pertaining to the Pygopodidæ.
• noun In herpetology, a lizard of the family Pygopodidæ.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) One of the Pygopodes.
• noun (Zoöl.) Any species of serpentiform lizards of the family Pygopodidæ, which have rudimentary hind legs near the anal cleft, but lack fore legs.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology One of the Pygopodes.
• noun zoology Any species of serpentiform lizards of the family Pygopodidae, which have rudimentary hind legs near the anal cleft, but lack forelegs.