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356 Mr. C. W. Andrews on Fossil Remains of 



One of the most notable specimens in tiie collection is ail 

 imperfect Ralline pelvis, which cannot be referred to any 

 species now living in the island, but which is closely similar 

 to that of Tribonyx mortieri, Gould, now living in Australia 

 and Tasmania. This specimen was found in the superficial 

 black earth. 



This^>e/m (PI. IX. figs. 4 & 5) of this bird exhibits typically 

 Ralline characters in the forms of the pelvic escutcheon and 

 of the posterior renal fossse. From the pelves of Porphyrio, 

 Ocydromus, and other Ocydromiue Rails (e. g. Aphanapteryx, 

 Diaphorapteryx, and Erythromachus) it is at once distin- 

 guished by the fact that the ilia in the pre-acetabular region 

 do not unite with the summit of the neural spines of the 

 sacral vertebrse throughout their whole extent, but, as in 

 Fulica and Gall'mula, in their middle portion the dorsal 

 borders curve down so as to leave the spines in that region 

 laterally exposed. From the pelvis of Porplnjrio the fossil 

 is further distinguished by the concavity from side to side of 

 the dorsal surface of the post-acetabular sacrum, and by the 

 relatively greater width of the posterior renal fossae. In 

 Ocydromus the whole of the posterior half of the pelvis is 

 narrower. In Fulica and Gallinula the length of the pelvis 

 in proportion to its width is much greater. On the other 

 hand, the points of difference from the pelvis of Tribonyx 

 are trifling, the only noticeable ones being the rather greater 

 width of the pelvic escutcheon, and, in correlation with this, 

 the wider posterior renal fossse, and the smaller size of the 

 supra- acetabular ridges of the ilia. In the Australian bird, 

 moreover, there is a rather deep depression in the ilia imme- 

 diately in front of the acetabulum and above the pectineal 

 process ; this depression is wanting in the fossil. 



There is no doubt that this bird is generically distinct 

 from any form now found in Madagascar, but the similarity to 

 the Australian Tribonyx is so great that it may be provision- 

 ally referred to that genus, though very probably, when the 

 skeleton has become better known, it may prove to be distinct. 

 The specific name Tribonyx roberti may be adopted for it. 



The dimensions of the pelvis, together with those of 

 Tribonyx mortieri and some other Rails, are as follows : — 



