139
TRIBONYX ROBERTIANDREWS.
- Tribonyx roberti Andrews, Ibis 1897, p. 356, pl. IX, figs 4-7.
This bird is described from an imperfect pelvis, a perfect left tibio-tarsus and a femur. The pelvis differs from that of T. mortieri in not having the deep depression in the ilia in front of the acetabulum and above the pectineal process. It also differs in having a rather wider pelvic escutcheon and wider renal fossal, and the supra-acetabular ridges of the ilia are smaller than in the Australian bird. The beautifully-preserved left tibia differs from that of T. mortieri in having the intercondylar groove wider and shallower, the inner condyle less massive, thus making the difference between the inner and outer condyle more marked; T. roberti also has the shaft immediately above the extensor bridge wider, the bridge itself less oblique, and the fibular crest is longer.
The measurements are:—
| Pelvis. | ||
| Length of Ilium | 82 | mm. approx. |
| Least width of acetabular region of Pelvis | 14 | " |
| Width at Antitrochanter | 40 | " |
| Width at anterior angle of Pelvic Escutcheon | 36 | " |
| Width at Posterior angle of Pelvic Escutcheon | 40 | " |
| Length of Sacrum | 68 | " |
| Tibia. | ||
| Length | 143 | mm. |
| Width at distal extremity | 12 | " |
| Width at middle of shaft | 7 | " |
| Femur. | ||
| Length | 83 | mm. |
| Width at distal extremity | 17 | " |
| Width at middle of shaft | 7 | " |
Habitat: Sirabé in C. Madagascar.
