GENUS OF BIRDS. 
451 
ing posterior foramen. In none of these genera is the exterior tibial surface de- 
flected anteriorly, and in none of them is it elevated into a transverse ridge poster- 
iorly. The corresponding region in Gastoruis is imperfectly known. So lar as 
described by Lemoine,^ it agrees in these points with the other Ratitae, as does ahso 
Diatryjna. which has also but a single hypotarsal crest. 
Comparison with the Steganopodes shows much greater resemblances. The an- 
terior aspect of the bone is almost exactly like that of Pelecamis. The posterior 
aspect resembles that of none of the order, in the absence of most of the tendinous 
grooves. This part of the bone resembles nearly that of some genera of Callinm, 
especially Meleagris, where, however, the tendinous groove is enclosed. This genus 
differs from it in every other respect, including the non-pneumatic shaft. Compari- 
son with birds of the cretaceous period reveals a single point of resemblance to Hes- 
perornis. This is the ridge-like elevation of the anterior part of the external tibial 
facet, which is in both genei’a connected with the intercondylar tuberosity. In no 
other respect is thei’e any resemblance. No resemblance between this bone and 
that of the Dodo can be detected. 
If we compare this bird with the Steganopodes we have as points of agreement 
the anteriorly deflected external tibial facet, the grooved ])osterior face, the narrow 
internal and wide external hypotarsal processes, and the high degree of pneu- 
maticity. As additional points of resemblance to Pelecamis we have the huge an- 
teidor pneumatic foramen, and the narrow open groove of the external face. The 
posterior foramina have a similar situation. But the presence of a single tendinous 
groove indicates a wide difference of character, and the transverse ridge of the ex- 
ternal tibial facet is scarcely indicated in any genus of Steganopodes. 
In view of the above facts we may suspect real affinities with the Steganopodes. 
combined with affinities to more primitive birds with a simple h3potarsal structure. 
The Steganopodous foot, with its long second digit turned forward as in other ver- 
tebrates, is itself the most primitive foot among the Eurhipiduran On the charac- 
ters adduced I propose the genus Cyphornis, and name the species C. magnus, 
which may be regarded as defined by the measurements and other specific characters 
above enumerated. It is saicF that the birds described by Owen under the names 
of Argillornis and Lithornis^ from the Eocene London Clay are allied to the Ste- 
ganopodes. In none of the throe species of these genera is the tarsometatarse pre- 
served. Thej' are all much smaller than the present bird. 
The characters of Cyphornis indicate that the bed from which it was obtaine<l, 
is not older than Eocene nor later than Oligocene. 
As regards its habits it maybe said that the pneumatic character of its foot bone 
renders it improbable that it depended on this member for habitual locomotion on 
land. In all the birds of terrestrial habit which I have examined, and of which I can gain 
‘ Recherch&s sur le.s Oiseaux fossiles des Terraiues Tertiaires iufeiieur.s ties Kinin.iiK de Kcuuh, PI. 
I, p. 53. 
2 By Lvdekker in Newton’s Dictionary of Birds, I. p. 283. . i .>j c- t- i 
’Annals and Magazine of Nat. History, XIV, p. 26.3. Trairs. (leol. t?oc. London, 2d Ser., \ ol. 
VI, p. 206. 
59 JOUEN. A. N. S. PHILA., VOL. IX. 
