• CACOPS ASPIDEPHORUS 275 



concavity below its middle. It has a distinct and rather protuberant rim^ 

 save at the upper posterior part. Its upper border on the ilium is marked 

 by a small but distinct process overhanging the concavity. The lower 

 margin on the ischium is very prominent, forming an angular projection 

 to the full width of the bone, while the stout expansion of the pubis in 

 front limits the deepest concavity of the acetabulum. The shape of the 

 acetabulum would indicate that the chief pressure of the femur was di- 

 rected nearly horizontally and a little backward. The lower rim is nearly 

 horizontal, deeply concave antero-posteriorl}'-, overhanging the almost 

 horizontal outer surface below. The pubes flare outward on each -side 

 in front from a subangular line, running downward and inward through 

 the inner orifice of the obturator foramen to either side of the median 

 emargination of the front border. The triangular surface either side 

 thus limited looks at an angle of about 45 degrees upward from the hori- 

 zontal position of the pelvis and slightly inward, and is gently convex 

 from side to side. The under surface on the sides of the conjoined pelvis 

 is nearly horizontal laterally, descending in the middle into a broad ob- 

 tuse ridge, broadest and deepest a little in front of the middle. In front 

 the downward curvature of the pubes leaves a concavity, at the bottom 

 of which is the external opening of the obturator foramen, very near the 

 middle of the pubis antero-posteriorly, and opposite the greatest pro- 

 tuberance of the pubic margin, not far from the border of the acetabulum. 

 The front border of the pubes is roughened for cartilage. The sutures 

 separating the elements are very clearly shown in the present specimen. 

 Those between the ilium and ischium and pubes begin on the margins 

 near the middle of the convexities described and run downward to meet 

 a little below the middle of the acetabulum, that for the ischium being a 

 little longer than the one for the pubis. The puboischiadic suture runs 

 directly inward through the deepest part of the lower margin of the 

 acetabular rim, the length of the ischia below being about a fifth greater 

 than that of the pubes. The depth of the lower pelvic border is due 

 solely to the breadth of the symphysis, the upper surface of the pelvis 

 in the middle showing no corresponding concavity. 



Femur (plate 13, figures 2-5). — The femur is remarkable among 

 temnospondyles for its slenderness and the great development of the 

 adductor crest. The proximal articular surface has its transverse diame- 

 ter but little greater than the antero-posterior one, narrower on the outer 

 side, more convex on the inner, where the articular surface extends more 

 on the ventral side. The digital fossa is small and shallow. The ad- 

 ductor crest arises near the upper part of the bone, is directed outward 

 for a short distance, and then is nearly straight to its distal end near the 



