Permian of New Mexico. 395 



ilium had been broken off and turned aside before fossiliza- 

 tion. Both femora are closely articulated in the acetabula, 

 directed obliquely dorsad and cephalad. The pubes and ischia 

 lie in a subhorizontal position, with a protuberant carina along 

 the middle, deeper anteriorly. This keel, however, is not 

 formed by the downward deflection of the margin of the 

 bones, but by the increased depth of the symphysis, as will be 

 seen from the cross sections of the figure, sections made at 

 points of fracture in the specimen. The ischia have an 

 angular margination in the middle, the sides curving outward 

 and upward to the rounded posterior angle. The sutural 

 division between ischium and pubis is at about two-fifths of 

 the length from the front end of the pelvis. The pubic fora- 

 men is remarkably large at the bottom of a rather deep fossa 

 situated a little back of the ischio-pubic suture, and not far 

 from the acetabular border. The acetabulum is deep and 

 large, with an overhanging, nearly horizontal roof-like pro- 

 cess, at the upper posterior part. In life the cavity looked 

 almost directly outward. The ilium is relatively small; it is 

 flattened and thinned above and in front, with a rather stout, 

 narrow process directed backwards and a little outward, nearly 

 horizontal. Upon the whole, the structure of the pelvis is 

 nearly identical with that of Diadectes and l^ariotichidm, and 

 even of Eryops and Cacops, save in the form of the ilium ; in 

 Diadectes, broader above and not produced backward ; in the 

 temnospondyls without iliac projections either in front or 

 behind. While there is but a single sacral vertebra in Limno- 

 scelis and Diadectes, in Cacops there are two, a precise reverse 

 of what has always been supposed to be diagnostic charac- 

 ters of these two classes of vertebrates. The femur is of the 

 characteristic Diadectes type, short, stout, and expanded, with 

 a heavy, protuberant trochanter, and a large digital fossa. 

 The trochanter has a large facet, 20 or more millimeters in 

 diameter, looking backward, and is rugose ; the adductor ridge 

 is pronounced and oblique. The tibia, like the femur, is short 

 and stout, with a greatly expanded upper end, and a strong 

 cnemial protuberance. The outer side is deeply concave in 

 outline, the inner nearly straight. The lower extremity is much 

 thickened. The fibula is a more slender bone than the tibia, 

 and is longer. Its proximal end is thickened and subquadrate 

 in shape ; the lower end is thin and considerably expanded. 



Hind Foot. — As already stated, the foot bones of specimen 

 No. 811 were more or less weathered. From the wash, numer- 

 ous toe bones and the ends of the epipodials with attached 

 tarsals had been gathered up by Mr. Baldwin, and some of 

 them still retain enough of their original matrix to show their 

 relationships, but how many of them are irretrievably lost 



