PEOFESSOK OWEN ON THE GENUS DINORNIS. 183 



of that plate upward, and to turn the horizontal under surface, 20, into a vertical 

 outer surface of the bone, which rapidly gains in depth, and has its upper part bent 

 inward, to complete with the vomer, 13, the hind wall of the palato-narial canal. At 

 the outer and back part of the canal the palatine is thickened at its lower part to arti- 

 culate with the pterygoid, 24. 



The vomer is bifid, as in I), ingens and as in the first-described skull of J), crassus 

 {torn. cit. pi. xi. fig. 3, is). The parial plates of the vomer overlap the sides of the 

 presphenoids, 9, of which the anterior apex, 9', coalesced with the narial septum, 

 projects beyond the vomer, and partially divides the prepalatine vacuity. The anterior 

 ends of the halves are overlapped by the vomerine processes of the premaxillaries. 

 Each half of the vomer consists of a deep vertical bony plate, almost meeting below the 

 presphenoidal rostrum, expanding at both ends anteriorly to join the premaxillary 

 and the palato-maxillary plates, and there bounding the palato-nares anteriorly ; pos- 

 teriorly expanding in a greater degree, and curving outward and forward to join the 

 palatines, and form the posterior boundaries of the palato-nares. These apertures are 

 each 1 inch 7 lines in length, 5^ lines in breadth ; the breadth across both apertures is 

 1 inch 11^ lines, the additional half line giving the interval between the halves of the 

 vomer. 



The suture between the vomer and palatine, as one looks down upon the skull's base, 

 runs along the bottom of the vomero-palatine or postnariiil fossa, along a shallow 

 channel there ; it seems obliterated near the postero-external rather thickened border 

 of that fossa. From this border the pterygoid process of the palatine is divided by a 

 triangular shallow depression. The pterygoid is short, three-sided, with the sharp 

 angle between the inner and outer facets of the under surface of the bone turned down- 

 ward, and continuing backward a similar ridge on the under part of the palatine. 



The pterygoid has an extent of articulation with the tympanic of more than half an 

 inch in D. maximus. 



In this, as in smaller species of Binornis, well-ossified sesamoid bones added to the 

 leverage of the muscles of the foot by their interposition at the back part of both the 

 proximal and distal joints of tlie metatarsal segment. The tibio-tarsal sesamoid 

 (Plate XXXI. figs. 0-6) works upon the shallow rounded surface at the back part of 

 the ectocoudylar fossa of the metatarsus. It is an elongate, trihedral, conical bone, with a 

 slight sigmoid flexure. The end representing the base (fig. 3) is external or looks fibulad ; 

 the opposite or inner end, or apex, is obtuse. The base is triangular, almost flat, with 

 rough ligamentous marks. The two articular sides are half concave half convex length- 

 wise ; on the narrower side the convexity is next the base, and the reverse on the 

 broader side. The non-articular side is almost flat and has faint linear and irregular 

 impressions. In one specimen the ligamentous or tendinous attachments to the base 

 were partially ossified. 



Here 1 propose to conclude the task of restoration of Dinornis maximus. The liberal 



