10 PROFESSOR OWEN ON THE GENUS DINORNIS. 
The second (rv. 2), the third (1v. 3) and the fourth (1v.4) phalanges repeat the cha- 
racters of their homologues in the Palapteryx robustus, in regard to their shortness and 
breadth, and the flattening of their upper surface: the under border of the proximal 
joint of one phalanx underlaps the trochlea of the preceding phalanx, and the distal 
joint of the fourth phalanx is divided by the median groove to which a median ridge on 
the proximal joint of the last phalanx is adapted. 
The extent of the articular surfaces of all the joints of the toes of the Palapteryx dro- 
mioides shows a corresponding freedom and extent of motion of those toes. 
The bones of the foot restored and figured in PI. III. fig. 1, accord by their propor- 
tions with the tarso-metatarse of the Dinornis rhetdes, the distal trochleze of which are 
quite adapted to the proximal joints of the proximal phalanges. 
The tarso-metatarse of the Dinornis rheides differs from that of the Palapteryx robustus, 
by the absence of any rudiment of the ectocalcaneal process; by the greater elevation 
of the entocalcaneal process and its equality of size with the mesocalcaneal process ; and 
by the presence of a tubercle at the middle of the inner border of the inner concavity for 
the tibia. There is no trace of a depression for the articulation of the back-toe. 
The phalanges differ from those of the Palapteryx dromioides, not only by their thicker 
proportions, as shown in PI. III. fig. 1, but by the less deep divisions of the trochlear 
surfaces. In the short cuboidal phalanges, 3 and 4, of the outer toe (rv), the distal 
trochlea presents an almost uniform convexity : and the ungual phalanx of this toe is di- 
stinguished from that of the other toes by the uniform concavity of its proximal surface. 
The greater strength of the toes of the Dinornis casuarinus accords with the superior thick- 
ness of the tarso-metatarse, compared with that bone in the Palapterya dromioides ; and 
a corresponding difference in the habits of the two birds may be inferred from these dif- 
ferences in the structure of the feet. 
Description of the Femur and Tarso-metatarse of the Aptornis otidiformis. 
In my Memoir on the Dinornis of 18431, I described and figured a tibia obtained by 
the Very Rev. Archdeacon Williams from a fluviatile deposit in the North Island of New 
Zealand, and referred it provisionally to a species of Dinornis under the name of Dinornis 
otidiformis. In a subsequent Memoir’ read before the Zoological Society in 1848, I de- 
termined the tarso-metatarsal bone which articulated with that tibia, and pointed out 
some characters of the tarso-metatarsal bone which indicated the generic distinction of 
the bird to which it belonged, from the Dinornis, and accordingly I proposed for it the 
name of Aptornis*. I am now enabled further to advance the knowledge of the charac- 
ters of the bones of the leg of this genus and species by a description and figures of the 
femur (PI. III. figs.3 & 4). This bone, which measures six inches three lines in length, 
has a straight, strong, subcylindrical shaft, with which the short and thick neck support- 
* Zool. Trans. iii. Part iii. p. 235. pl. 25. figs. 5 & 6; pl. 26. figs. 5 & 6. ? Ib. p. 347. 
* By syncope for “ Apterygiornis,” from a priv., rrépvé wing, ipris bird. 
