Springing, I hazard, from the stegocephalia, the ancestor of the frogs, these batrachians followed a different line of evolution and acquired the upright position just as man did his from the four-footed folk.
The great staring eyes, the shape of the muzzle were frog-like, but the highly developed brain had set upon the head and shape of it vital differences.

The forehead, for instance, was not low, flat, and retreating--its frontal arch was well defined.

The head was, in a sense, shapely, and with the females the great horny carapace that stood over it like a fantastic helmet was much modified, as were the spurs that were so formidable in the male; colouration was different also.

The torso was upright; the legs a little bent, giving them their crouching gait--but I wander from my subject.[1] They set their burdens down.

Larry looked at them with interest.
"You surely have those things well trained, Lakla," he said.
"Things!" The handmaiden arose, eyes flashing with indignation.