DEVELOPMENT OF THE SKULL IN THE OSTEICH TEIBE. 167 



as large as that of Porphyrio poliocephalus. In this vomer the hinder forks are larger 

 than the body, which is slightly split at its apex : in its congeners this end is somewhat 

 clubbed; the vomer is lost from this very fresh IHnomis robustus (York specimen). 

 But the prevomer is well seen on one side ; and its suture with the intermaxillary and 

 its palatine zygomatic and ascending process are well shown : in the latter (ophidian) 

 process it agrees rather with the Rhea and the Cassowary than with the Emu, or the 

 African Ostrich. The prevomer of the Great Notomis is much broken ; but it agrees 

 with the Eails and many other typical birds in the manner in which it projects mesiad 

 of the palatine, as it overlaps it in front of the middle nares. The largest part of the 

 prevomer (the oblique lobe) is broken off in this fossil. 



But the intermaxillaries of these two types diverge fully as much as any part ; the 

 madrepore-like perforateness of the body of the bone shows the place of Dinornis robus- 

 tus ; the oblique sparsely-scattered holes in the bone of the Notornis are exactly such as 

 are seen in the smaller Notornis Mantelli, in Porphyrio, and Ocydromus, Crex, &c. The 

 lateral grooves, known to every tyro, are well marked in the photographs. They are 

 not present in the Notornis. In one thing these two gigantic forms agree, e. g. in the 

 size of the body of the bone ; but whilst in the Dinornis it is broadly-outspread, in the 

 Notornis it is pinched, decurved, and apiculate. But the nasal process in IHnomis only 

 reaches to the lacrymals, stopping in front of the broad ethmoid, and lying loosely over 

 the rest of the face, as in its congeners ; in the Notomis it reaches to the same transverse 

 line as the postfrontal spurs, and is sunken into the substance of the skull above, and 

 completely buries the ethmoid. Moreover, this process is thin and lath-like in Dinornis ; 

 it is a thick slab of bone in the Notornis. The nasals, as far as they are free, are quite 

 struthious ; in that family they end in a blunt style ; in the Notomis their sutures can be 

 well seen, and they are nearly half an inch wide, where they fit in between the frontals ; 

 they are crescentic in this their largest moiety, and curve round behind the nasal pro- 

 cess of the intermaxillary, which lies low down between them ; for the nasals are more 

 than flush with the top of the frontals. The Dinornis, like the Rhea and Emu {Dromceus 

 NovcB Hollandice), had scarcely any descending process to the nasal ; in the Notomis the 

 fragment of the root of this process shows it to have had precisely the same obliquity as 

 in the ordinary Rails. The frontal region is of extraordinary breadth in Dinornis 

 robustus ; and the brows are so completely shielded by the outgrowing of the frontals, 

 that the long superorbital process of the lacrymal has melted into the edge of the 

 frontal, a space only being left for the upper part of the small nasal gland. The bony 

 lowering of the brows is seen in other large massive forms, e. g. the Dodo (Didits), the 

 Adjutant (Leptoptilus), and the King Vulture (Sarcorhamphm). The edge of the post- 

 frontal is so much produced that the semicircularity of the superorbital rim is lost, and 

 a sinuous and somewhat notched outline results. The whole upper head is one broad, 

 gently convex shield-like mass, shelving down into the extremely wide and rather low 

 occipital region. The temporal fossae are not so well marked as in Struthio camelus, 

 and that notvdthstanding the far greater strength of the jaws. The thick, backwardly 



