10 PROFESSOR OWEN ON THE GENUS DINORNIS. 



The second (iv. 2), the third (iv. 3) and the fourth (iv.4) phalanges repeat the cha- 

 racters of their homologues in the Palapieryx rohustus, in regard to their siiortness 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 rhe'ides, the distal trochleae of which are 

 quite adapted to the proximal joints of the proximal phalanges. 



The tarso-metatarse of the Dinornis rhe'ides differs from that of the Palapteryx rohustus, 

 by the absence of any rudiment of the ectocalcaneal process ; by the greater elevation 

 of the entocalcaneal process and its equaUty 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 (iv), 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 Palapteryx 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 1843', 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, 1 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. pi. 25. figs. 5 & 6 ; pi. 26. figs. 5 & 6. = Il>. p. 347. 



' l?y syncope for " Apterygiornis," from apriv., 7rrepv£, xcinij, uprts bird. 



