82 



A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



edge extends downward and outward on to the shaft of the bone and forms a promi- 

 nent tuberosity near the lower edge of the concave space; from this point a low ridge 

 is continued on the posterior surface of the shaft until it disappears near the middle 

 of the bone. The articular face of the distal end has two parts; the inner is double, 

 being nearly divided by a notch on the anterior edge, which corresponds to the groove 

 on the anterior surface of the upper end of the tibia. The outer face is elongated 



Fig. 29. 



A. Lower view of pelvis of Diadeaes sp. X J. No. 1075 Univ. of Chicago. 



B. Pelvis of an unknown Diadectid. X J. No. 4848 Am. Mus. a, ilium; b, pubis; c, ischium. 



C. Right side of pelvis of Diadeaes sp. X \. No. 1075 Univ. of Chicago. 



at right angles to the head of the tibia and nearly separated from it. It supports 

 the fibula. 



The tibia is short with an especially heavy proximal end. This is partly divided 

 into two faces by a deep groove on the anterior face, to correspond with the two 

 faces of the femur. The distal articular face is inclined obliquely upward and 

 inward and is slightly crescentic in outline (fig. 30, b and c). 



The fibula in known 

 specimens is crushed flat; 

 it was probably fairly flat 

 in the natural condition. 

 The upper end is thin and 

 wide, but less so than the 

 distal. It was probably 

 concave on the inner side 

 to fit around the edge of 

 the tibia. The distal face 

 is set obliquely in opposi- 

 tion to the distal face of 

 the tibia (fig. 30, d). 



The feet (plate 7, fig. 

 1) are unfortunately very 

 poorly known; no speci- 

 men has been found with 

 any portion of the feet in 

 position. The figures show that all the bones were stout and heavy and that the 

 foot must have been very broad. The metapodials are heavy and the phalanges 

 very short. The number of phalanges is uncertain, but even if the animal is given 

 the primitive reptilian number, 2, 3, 4, 5, 4, such as Broom gives Pareiasaurus, or 

 2, 3, 3, 4, 3, as occurs in the specimen of Pareiasaurus in British Museum and in 



Fig. 30. — Diadectei phaseolinus. X J. No. 4684 Am. Mus. 



a, Posterior surface of the right femur; b, upper articular surface of tibia; c, anterior 



view of left tibia; d, fibula. 



