GIGANTIC BIED EEOM LOWER EOCENE BEDS. 153 



but these characters are more exaggerated, and the shaft of the bone is more flattened 

 from before backwards, than in the latter species. The inner condyle of G. klaasseni, 

 when viewed from the front, is seen to be almost vertical, and the inner and outer 

 tuberosities project well beyond the condyles, while in Dinornis crassus the inner 

 condyle is directed obliquely upwards and inwards, and the front of the condyles is 

 the widest part of the distal end of the tibio-tarsus. In D. crassus the intercondylar 

 margin of the trochlear surface rises higher than in the Croydon bird, and forms a 

 distinct and gently curved line, depressed in the middle, and continued over each 

 condyle. In consequence of this conformation the intercondylar depression is neither 

 so deep nor of the same form as it is in Gastornis klaasseni, and the general contour of 

 the condyles, in this front view, is markedly different in the two forms. In the latter 

 the condyles are laterally compressed, while in Dinornis they are wide, and shaped 

 somewhat like an hour-glass. The indenture of the inferior trochlear surface, as seen 

 from the front, in Gastornis Maasseni (PI. XXIX. fig. 7,b) is at about one third the 

 width of this surface from the outer side, while in Dinornis crassus the deepest 

 indenture is towards the inner side. 



The femur of Dinornis does not present the peculiarities which characterize that of 

 Gastornis. The trochanter stands above the articular head and the superior articular 

 surface, as it leaves the head, curves upwards ; while in Gastornis, as we have seen, the 

 superior articular surface passes obliquely downwards. The anterior crest in Dinornis 

 is not so well developed, and extends only a short distance along the shaft. 



The large fossil bird from Australia, Dromornis (Owen, Zool. Trans, vol. viii. p. 381, 

 and vol. x. p. 186), has the superior articular surface of the femur nearly horizontal, and 

 therefore, in this particular, approaches somewhat to the Gastornis ; but the other parts 

 of the bone are unlike. At first sight the tibio-tarsus of Dromornis seems to resemble 

 that of Gastornis ; but there is no evidence of the supratendinal bridge having been 

 ossified, and the canal is in the middle of the bone. 



The great Epiornis of Madagascar is less like Gastornis than the extinct forms already 

 noticed. Little need be said concerning the smaller birds, which have become extinct 

 within comparatively recent times, such as the Solitaire, Dodo, Aptornis, Notomis, and 

 Cnemiornis, for only the last of these (and possibly Notomis) makes a near approach to 

 Gastornis in the form of its tibio-tarsus. 



Cnemiornis is evidently nearly related to the Geese of the present day, and agrees 

 with them in most of those characters, to be presently pointed out, which are believed 

 to show some affinity between Gastornis and the Anserine birds {Chenomorphw) . 



V. — Gastornis compared with Recent Birds. 

 M. Hebert was impressed with the close resemblance between the Meudon tibio- 

 tarsus and that of the Swan and the Goose, and this resemblance is even more marked 

 in the Croydon fossils. Taking the tibio-tarsus of the Common Goose for comparison, 



2a2 



