The most distinctive feature is the narrowing of the manus and the great elongation (. I72 m.) of the metapodials and phalanges of the second digit, suggesting the rapid grasping power of agile and delicate prey. This feature, combined with the prehensile character of the somewhat enlarged an-terior teeth, the extreme lightness of the skeleton, the cursorial structure of the hind limbs, the balancing power of the tail, suggest the hypothesis that the animal may havebeen adapted to the pursuit of the Jurassic birds; in allusion to this supposed habit the genus may be named Ornitholestes, or'bird robber,'as suggested by Dr. Theodore Gill.