8 PROFESSOR OWEN ON THE GENUS DINORNIS. 



its breadth than the preceding (iv. 3) : the proximal surface is divided by a less promi- 

 nent ridge, and the distal one is still more feebly impressed by the median channel. 



The ungual phalanx (iv. 5) consequently may be distinguished from that of the other 

 toes by the almost uniform concavity in the vertical direction of its articular surface. 

 It is the smallest of the three ; the outer surface is more extensive and is flatter than 

 the inner one. In its lateral grooves and general downward curvature it agrees with 

 the ungual phalanges of the toes iii and ii. 



The ungual phalanges are of great strength : the base of the cone bears the same pro- 

 portion to its length as in the phalanx which terminates the strongest of the two toes 

 of the Ostrich (in. 4, fig. 7) ; and it exceeds that in the ungual phalanges of the Rhea 

 and Emeu : notwithstanding which, the claw phalanges of the Palapteryx show a degree 

 of downward curvature greater than in the Ostrich or Rhea, and such as is rarely seen 

 except in claw-bones of more slender proportions. 



The breadth of the base, or articular surface of the ungual phalanx of the middle toe iu 

 the Palapteryx robustus is one inch four lines, the length of the phalanx being three 

 inches: the same admeasurements in the ungual phalanx of the inner toe, ii, give one 

 inch three lines, and three inches, and in that of the outer toe, iv, one inch one line, 

 and two inches four lines. These proportions, with the downward curvature of the 

 claw-bones, indicate that the powerful claws with which they were sheathed must have 

 been put to uses requiring great force, analogous to those for which the similarly pro- 

 portioned claw-bones of the Apteryx are adapted. In this small species the power of 

 scratching up the soil is exercised to such a degree that it excavates a burrow for its 

 safe habitation : in the larger allied extinct species the rasorial actions would doubtless 

 be restricted to the acquisition of food : and the ascertained structure of the foot thus 

 accords with and bears out the conclusions deduced from the structure of the bones of 

 the neck and head. 



Amongst the toe-bones of smaller dimensions, which from time to time were trans- 

 mitted to me, I soon found homologous ones presenting different proportions ; and, 

 finally, by means of the rich accession of specimens due to the enlightened exertions of 

 Col. Wakefield, I have been enabled to recompose the entire feet of two species cha- 

 racterized by those different proportions of the phalanges. One of these feet is repre- 

 sented in PI. II., the other in PI. III. 



As the coalesced metatarsals might be expected to manifest the same general propor- 

 tions as the toes they sustained, I have referred the more slender phalanges to the Pal- 

 apteryx dromioides, and the more robust ones to the Dinornis rheides, the articular 

 condyles of the metatarsi of these species bearing the closest correspondence with the 

 joints of the proximal phalanges to which they have been respectively adjusted in the 

 specimens represented of the natural size in Plates II. & III. 



The metatarse of the Palapteryx dromioides shows the articular depression for the 

 small back-toe : but the bones of this toe have not yet reached me. 



