172 ODONTORXITHES. 



slightly roughened, but not more so than in Colymbus. The precise length 

 of the femur, and, of course, its length as compared with that of the tibia, 

 cannot be determined; but the leg was evidently more strongly built than 

 in Ichthyornis, while the wings appear to have been less powerful. 



The femur in the type specimen of Ichthyornis has the following 

 dimensions : 



Measurements of Femur. {Ichthyornis dispar, No. 1450.) 



Length of femur, 30.5 mm 



Diameter of head, 2.8 



Greatest diameter of proximal end, 6.0 



Diameters of shaft, 3.0-2.5 



Transverse diameter of distal end, 6.0 



Antero-posterior diameter of inner condyle, 4.0 



Antero-posterior diameter of outer condyle, 4.5 



Antero-posterior diameter at fibular articulation, 3.5 



The Tibia. (Plates XXV and XXXIII.) 

 The tibia of Ichthyornis dispar is a slender bone of moderate length. 

 The cnemial process is but little developed, and only slightly elevated 

 above the articular face of the bone. The shaft was hollow, with rather 

 thin walls, and was gently curved inward toward its distal end, rather 

 more strongly than in the Tern. In section, the shaft was transversely 

 oval. The fibular ridge arises just below the outer articular face, and is 

 continued downwards until broken off by a fracture of the shaft, as seen 

 in plate XXV, figs. 5-8. It is probable, however, that the ridge continues 

 but a short distance farther on the shaft. The distal portion of the shaft 

 preserved shows no trace of a fibular ridge. It is gently curved inward, 

 and expands gradually to the articulation. Toward the distal end, the 

 shaft becomes more flattened, and is excavated in front for the passage of 

 tendons, which were not, however, kept in place by an osseous supraten- 

 dinal bridge. The articular face has been somewhat injured by compres- 

 sion in the type specimen (nirmber 1450), but seems to have resembled 

 in general form that seen in the Tern, although of comparatively less 

 antero-posterior diameter. 



