PROFESSOR OWEN ON THE GENUS DINORNIS. 7 



the middle : the section of the middle of this phalanx would be nearly a semicircle, the 

 under surface being flat transversely : the pits for the lateral ligaments, near the distal 

 end of the bone, are large and well-marked : the median depression of the distal trochlea 

 is shallower than in ii. 2. The proximal surface of the ungual phalanx is consequently 

 marked by a much more feeble median vertical prominence, and it is broader and of a 

 more symmetrical form than that of the ungual phalanx of the inner toe (ii. 3) ; it is 

 very little longer than that phalanx, and in other respects closely resembles it. 



The proximal phalanx of the outer toe (iv. 1) is characterized by its unsymmetrical 

 proximal surface and its great breadth in proportion to its length. The proximal arti- 

 cular surface is less expanded in proportion to the shaft than in ii. I. The median con- 

 cavity of that surface is smaller in proportion to its peripheral convexity : the inner 

 moiety of the surface has a much greater vertical extent than the outer one, its lower 

 angle being produced downwards and backwards, as shown in fig. 3 : a deep notch di- 

 vides it from the corresponding part of the outer surface ; a broad rough tract extends 

 forwards from the lower half of the outer surface along half the extent of the shaft : the 

 similar rough tract from the lower angl6 of the inner part of the proximal articulation 

 is narrower and of less extent. The smooth under surface of the shaft is slightly concave ; 

 the upper surface is slightly concave lengthwise, convex transversely. The distal tro- 

 chlea is divided by a deeper median vertical groove than in iii. 1, and the inner con- 

 vexity is broader, whilst the outer one is the most prominent : the inferior boundary of 

 the distal trochlea is sharply defined and almost straight, not notched in the middle as 

 in III. 1 and ii. 1. The second phalanx (iv. '2) is almost as broad as it is long. The 

 inner concavity of its proximal trochlea is the broadest : the upper surface extends 

 straight from the proximal to the distal trochlea, and it is less convex from side to side 

 than in in. 2. The under surface is nearly flat, and presents a ridge near to and nearly 

 parallel with the lower margin of the proximal trochlea. The large and deep pits for 

 the lateral ligaments occupy nearly the whole of the lateral surfaces of the phalanx. 

 The distal trochlea is proportionally broader in comparison with its vertical extent than 

 in III. 2 or ii. 2 ; it is less contracted above than in in. 3, and is also more deeply im- 

 pressed by the median channel : the inner division is the broadest. 



The third phalanx (iv. 3) viewed from above is broader than it is long ; but the pro- 

 duction backwards of the inferior border of the proximal articulation makes its extreme 

 length rather greater than its breadth : the section through the middle of this phalanx 

 would be nearly quadrate, the upper surface being broader and flatter than in any of 

 the previously described phalanges. The under surface developes a ridge along the 

 outer half of the inferior border of the proximal articulation : the inner concavity of that 

 articulation is the broadest. The ligament-pits occupy the whole lateral surface. The 

 distal articulation is much broader than it is deep, and the median channel is wide and 

 shallow ; the inner convexity is the broadest. 



The fourth phalanx (iv. 4), besides its smaller size, is shorter above in proportion to 



