AND AVKS OF NOIiTH AMERICA. 



122-c 



actors. The proximal extremity resembles that of the Crocodilia, while the distal is truly 

 Dinosaurian, approaching Megalosaurus. There is no distinct head, the whole extremity 

 is compressed, and the cxtremital surface concave in its long axis. It overhangs the shaft 

 on the inner side and forms a knob which is decurved, and contracts below abruptly to 

 the shaft. The external margin is a subacute ridge ; the small trochanter is represented 

 by a short ridge which is but little defined on the inner side, and which sinks to the gen- 

 eral level some distance below the head. The compression of the shaft changes to a 

 sub-cylindric form, and just above this point the large third trochanter projects. It is 

 short ; inside of it a large rugose surface indicates the insertion of a powerful muscle. 

 Near the distal extremity the shaft is compressed transversely. The articular face of the 

 condyles is rather flat. The outer has the least posterior production, and has a contin- 

 uous exterior face. The inner is divided exteriorly, near the posterior extremity, by a deep 

 groove, which is continued obliquely forward and inward on the articular face. The 

 anterior part of this condyle is strongly convex. The posterior is narrow and turned in- 

 wards and backwards to a sharp edge. This portion is outlined by the above mentioned 

 groove, and forms a narrow ovate in section. The popliteal groove is quite deep, and the 

 trochlear scarcely marked. 



The tibia and fibula are broken. Of the first, a piece of the proximal portion alone 

 remains ; of the latter, a piece is broken from the middle of the shaft. The head of the 

 tibia is flattened by pressure. The spine or crest is very prominent, but not so much so 

 as in Laflaps, and is much curved outwards. The posterior angle of the proximal extremity 

 is prominent, and the prominence to which the fibula is applied marks the anterior third 

 of the long diameter of the head in its present condition. The anterior crest gradually 

 sinks to the shaft. The greater part of the latter is flat, as an impression in the matrix 

 indicates. The fibula is slender and oval in section, with very thin walls. At the distal 

 extremity it expands slightly ; the articular face is plane transversely, and moderately con- 

 vex antero-posteriorly. Proximally the shaft expands in the direction opposite to its 

 compression, giving the head a nearly equal extent in both directions. The articular 

 surface is directed obliquely downwards to the tibia, and is more or less grooved; a strong 

 rabbet extends round its posterior angle. 



The foot is in relation to the extremity of the leg, in a strongly flexed position. The 

 tarsal and metatarsal elements were somewhat separated by the strain, though in nearly 

 normal position. 



The cuboid bone alone remains of these. It is closely approximated to the fibula with 

 a small interval occupied by matrix between. The form is somewhat like that in the 

 genus Alligator, and it bears a similar relative size to the adjacent elements. It is a sub- 

 triangular piece with concave sides; the posterior angle, as it were, pinched. One lateral 



