. The Canadian field-naturalist. 104 The Canadian Field-Naturalist [Vol. XLVI construction than in Struthiomi- mtis and the bone wall is slightly thinner. The as- tragalus has a well de- veloped ascending process which extends up the anterior face of the tibia as far as the bone is preserved. The as- tragalus is quite large, as in Struthio- mimus but is so thoroughly united with the distal end of the tibia that no more details can be Bâ^Ungual of digit II, super- ior view. Natural size. Five metatarsals are preserved but, as in most Upper Jurassic and Cretaceous Theropoda, is repr
. The Canadian field-naturalist. 104 The Canadian Field-Naturalist [Vol. XLVI construction than in Struthiomi- mtis and the bone wall is slightly thinner. The as- tragalus has a well de- veloped ascending process which extends up the anterior face of the tibia as far as the bone is preserved. The as- tragalus is quite large, as in Struthio- mimus but is so thoroughly united with the distal end of the tibia that no more details can be Bâ^Ungual of digit II, super- ior view. Natural size. Five metatarsals are preserved but, as in most Upper Jurassic and Cretaceous Theropoda, is represented by only the distal portion of the bone and No. V by a proximal splint. The most outstanding characters of the pes are the inequality in length of the three functional digits, the pecu- liar specialization of the second digit and the lateral compression of the ungual phalanges to which the generic name alludes. Comparison of the hind feet, would suggest that Stenonychosaurus inequalis was about twice as large as Ornitholestes hermani. Osborn" gives a length of 117 mm. for metatarsal III of Orni- " Osborn, H. F. Bull. , Vol. 35, p. 737, 1916. tholestes whereas that element in S. inequalis has a length of 250 mm. The relative length of digit III when compared with metatarsal III is con- siderably shorter than shown by Osborn for Ornitholestes. It is also proportionately shorter than in Macrophalangia canadensis but is longer than in Struthiomimus. In outlining the charac- ters of the Coeluridse, Matthew and Brown state the unguals of the pes are not compressed but in Stenonychosaurus they are strongly compressed for unguals of the hind feet. These unguals are very unlike those usually seen in the hind feet of theropodus dinosaurs. Had they been found dissociated they would doubtless have been regarded as pertaining to the manus as was done by Lambe, who figured and described similar bones as pertaining to the manus of Ornithomimv^ altvs^^. These are all
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