I originally found out about these guys in an older book on wildlife, and it had this close-up photo of the creature's head. I wasn't able to find the same image online, though. As the name suggests, they are reptiles and not worms or amphibians.
The head is stout, not set off from the neck, and either rounded, sloped, or sloped with a ridge down the middle. Most of the skull is solid bone, and they have a distinctive single median tooth in the upper jaw. They have no outer ears, and the eyes are deeply recessed and covered with skin and scales. The body is elongated, and the tail truncates in a manner that vaguely resembles the head. Their name is derived from Amphisbaena, a mythical serpent with a head at each end. The four species of Mexican Mole Lizard, genus Bipes, are unusual in having a pair of forelimbs, but all limbless species have some remnants of the pelvic and pectoral girdles embedded within the body musculature.
The skin of amphisbaenians is only loosely attached to the body, and they move using an accordion-like motion, in which the skin moves and the body seemingly just drags along behind it. Uniquely, they are also able to perform this motion in reverse just as effectively.Wikipedia article here: http://en.wikipedia.org/wiki/Amphisbaenia
Is it just me, or do they look a bit like living, disembodied penises? o_O