290 PATAGONIAN EXPEDITIONS! PALAEONTOLOGY. 



larger sacro-sciatic foramen, while the anterior expansion is more gradual. 

 The dorsal branch of the ischium is very short and depressed, broadening 

 abruptly behind the acetabulum, thus making the peduncle extremely 

 short, and the tuberosity is quite prominent ; the ventral portion of the 

 ischium is relatively much longer than in Hapahps, so that the principal 

 diameter of the obturator foramen is dorso-ventral, instead of antero- 

 posterior. The pubis is a slender rod, which is considerably longer and 

 less oblique than in Hapahps, and the symphysis, which is formed by 

 both pubes and ischia, is quite elongate. Owing to the length of the 

 pubes and ischia the pelvic opening has a different shape from that of the 

 last named genus, the dorso-ventral diameter exceeding the transverse. 



MEASUREMENTS. 



Pelvis, length 283 Obturator foramen, dorso-ventral di- 



Ilium, length 184 ameter 073 



Ischium, length 109 Pelvic opening, dorso-ventral diameter. .117 



Acetabulum, antero-posterior diameter .051 " " transverse diameter... .095 



" dorso-ventral diameter . . .039 Sacro-sciatic foramen, length 06 1 



Obturator foramen, antero-posterior di- 

 ameter 055 



Hind-Limb. The bones of the hind-leg differ considerably from those 

 of Hapahps. The femur (Plate XLIX, fig. 3), which has been consider- 

 ably distorted by pressure, is of nearly the same length as in H. longiceps, 

 but is notably more slender and less flattened ; the large, hemispherical 

 head rises well above the level of the great trochanter and presents more 

 proximally, less directly inward ; the sulcus for the round ligament is a 

 deep pit of elongate, narrow oval shape ; the great trochanter is heavy, 

 but not prominent and the digital fossa is almost obsolete, while the third 

 trochanter is distinctly smaller than" in H. longiceps. The shaft is more 

 rounded and slender than in any other of the Santa Cruz Gravigrada, 

 except Schismotherium. The rotular groove is short and narrow. 



The tibia (Plate XLIX, figs. 4, 4^) has a much more massive cnemial 

 process than that of H. longiceps, and the shaft is more slender, more 

 compressed antero-posteriorly and broadens less distally. A noteworthy 

 difference from all the known contemporary Gravigrada consists in the 

 absence of the prominent process, with its deep tendinal sulcus, from the 

 inner side of the distal end, and the internal malleolus is quite obsolete ; 

 the astragalar surface is narrower, but deeper planto-dorsally than in 



