PROFESSOR OWEN ON THE GENUS DINORNIS. 5 



The outer trochlea (iv) has a deep and rough depression on its narrow outer side, 

 and a wider depression on the side next the middle condyle ; but it is not impressed on 

 its under surface. The articular surface slopes from the inner to the outer side ; it is 

 moderately convex, with a faint median channel at its under part. The fore part of the 

 stem of this condyle presents a transverse groove between two transverse ridges. The 

 outer and hinder border of the trochlea is produced backwards. The rudimental meta- 

 tarsal of the hallux is figured of its natural size at fig. 1, and in figs 4 and 5, PI. I. : 

 it is of a rhomboidal form, is subcompressed, with its lower end enlarged and convex for 

 articulation with the proximal phalanx of the hallux. The opposite end of the bone is 

 obliquely truncate and roughened for the attachment of the ligaments which connected 

 it with the similarly rough articular depression on the entometatarse (ii). The outer 

 and anterior surface is slightly convex ; the inner and posterior surface is concave length- 

 wise : the bone is slightly twisted upon itself, this character being best shown by the 

 direction of the inner and longer border of the bone. It is longer in proportion to its 

 breadth than in the Apteryx, and it doubtless supported, as in that genus, a small 

 proximal phalanx terminated by an ungual one : the convex articular surface is im- 

 pressed by a shallow longitudinal groove, indicative of a trochlear articulation with the 

 phalanx. 



The phalanges of the three anterior toes are present in the same progressively in- 

 creasing number in the Palapteryx as in birds generally. The proximal phalanx (ii. 1) 

 of the second toe is distinguished from that of the third (middle) toe by the unsym- 

 metrical form of the proximal articulation, and from that of the fourth (outer) toe by its 

 greater length in proportion to its thickness. The form of the proximal articular surface 

 is given in fig. 3, at ii. 1 : the outer half of the surface is most extended from before back- 

 wards, and its posterior rounded angle is produced, and divided by a groove from the 

 corresponding part of the inner part of the joint. The under surface of the phalanx 

 presents a rough tuberosity near each of these angles, and the inner surface of the inner 

 angle is impressed with a pit for the insertion of the lateral hgament : the under surface 

 of the middle of the phalanx is flattened : the section of the bone at that part would give 

 almost a semicircle with the angles rounded off; but the inner side of the upper convex 

 part of the phalanx is rather more extended and sloping than the outer one. The distal 

 articulation is a convex trochlea describing rather more than a semicircle in the vertical 

 direction, and divided by a wide and deep median channel : the inner moiety of the 

 trochlea is rather the most produced : on each side of the distal end of the phalanx there 

 is a depression for the lateral ligament ; it is deepest on the outer side. 



The second phalanx of the second toe (ii. 2) has its expanded proximal articular 

 surface divided by a submedian vertical ridge into two concavities, the inner one being 

 broader in proportion to its vertical extent than the outer one, which shows reverse 

 proportions : the section of the middle of the shaft is subtriedral with rounded angles ; 

 the outer and inner sides converging more to the upper surface than in ii. 1, and the 



