PEOFESSOR OWEN ON THE GENUS DINOENIS. 235 



respective centrums, the ali- and orbito-sphenoids, in all birds. Anterior to these the 

 confluence with the prefrontals is marked in I), parvus by the outward extension of a 

 triangular plate of bone, indicative of the original base of the prefrontal neurapophyses, 

 which have coalesced into a single vertical plate, again expanding on each side to give 

 support to the bifid neural spine, or nasal bone. The upper expansions of the coalesced 

 prefrontals likewise undergo ankylosis with the posterior turbinals. The inferior 

 turbinals coalesce with the maxillaries, but remain free from the intervening part of 

 the presphenoid. 



On the upper surface of the skull (PI. LII. fig. 2) the sutural limits of the parietal 

 bone are obliterated. Laterally a low ridge defines the upper boundary of the temporal 

 fossa ; and the fore part of this ridge is continued forward and outward to form the 

 posterior angle of the three-sided, conical, downbent, obtuse postfrontal process. The 

 prosencephalic part of the conical roof does not rise above the level of the calvarium, 

 as in B. rlwides ' ; the postfrontal terminates less obtusely than in that species. The 

 temporal fossa is relatively wider and better defined, by a continuous ridge extending 

 backwards to the mastoid, than in any of the before-described skulls of Dinornis. The 

 rostral part of the premaxillary has nearly the same shape and proportions as in 

 B. rheides, being in both species relatively shorter than in D. robustus^ andD. ingens^; 

 but it is longer than in B. casuarinus*. The concave hind margin of the premaxillary 

 septum is excavated to receive the fore end of the presphenoidal rostrum, here forming, 

 or confluent with, the fore end of the septum narium (PI. LII. fig. 1, s). The lateral 

 grooves of the rostrum are continued nearer to the trenchant margins of that part than 

 in B. rheides. 



The upper median tract (ib. fig. 2, 22' ) is impressed at its middle third by a 

 narrow longitudinal furrow ; beyond this it expands laterally and thins off vertically, the 

 lamelliform hind portion fitting into the corresponding channel of the coalesced 

 nasals, which, in advancing forward, pass beneath the beginning of the nasal process 

 of the premaxillary. 



From the short maxillary diverge the malar process (fig. 1, 21) and the palatal process 

 (fig, 3, 21' ). The malar process, the malar bone (26), and the zygomatic or squamosal (27) 

 have, as usual in birds, coalesced to form a styliform zygoma, 2^ inches in length. 

 The malar presents a low angle to the postfrontal ; but the interval, or unossified hind 

 border of the orbit, is 4 lines in extent. From the inner side of the hind end of the 

 squamosal projects the tubercle adapted to the articular cavity on the tympanic. This 

 bone is relatively longer than in Binornis crassus, and has a longer orbital process (k)^. 

 There is a large foramen pneumaticum on the inner (mesial) side of the articular 



' Trans. Zool. Soc. vol. vii. p. 13-1, pi. xii. fig. 3, u. ^ Ibid. vol. v. pi. xi. fig. 1, 22. 



' Ibid. vol. vii. pi. XV. fig. 1. * Ibid. vol. vii. pi. xiii. fig. 1. 



' Compare with pi. xi. fig. 6, Trans. Zool. Soc. vol. vii. 



2o 2 



