PHYLOdEXY OF THE PAL.EOUNATILE AXD XEOGXATH.E. 203 



In Bhea the nasal must be regarded as liolorhinal, though the maxillary process is 

 absent. Inasmuch as this process, when ]n"esent, serves as the boundary, caudad, of 

 the anterior nares, its place must be regarded as being filled by a vertical spike of bone 

 arising from the maxillo-palatine process to the anterior border of the lachrymal. In 

 Struthio this vertical spike— in Rhea separating the anterior nares from the laclirymo- 

 nasal fossa — is represented by a ligament which is attached dorsad to the free end of 

 the maxillary process of the nasal. 



In Struthio the nasal is holorhinal (PI. XLII. fig. .3). Its maxillary process is 

 well developed, and continued downwards on the maxillo-palatine by ligament. 



The Tinamida' may be regarded as holorhinal, though the nasal cleft has extended 

 backwards so far as to lie level with the free end of the nasal in-ocess of the premaxilla. 

 The maxillary process is not wanting as in Rhea, thougli reduced to a mere vestige. 

 The nasal cleft is bounded externally by a vertical, bony rod, representing the 

 maxillary spike found in Rliea. It differs therefrom in being rod-like, very slender, 

 and is perfectly free. Above, it articulates, by means of a short inturned process, with 

 the anterior border of the lachrymal and the vestigial maxillary nasal process, whilst 

 ventrally it articulates with the extreme postero-external border of the maxillo-palatine 

 process where it joins with the rod-shaped portion of the maxilla. This vertical rod 

 was regarded by Kitchen Parker as the maxillary process of the nasal. It is, however, 

 in all the skulls I have examined, quite distinct from tliis. 



The lachrymal, in Droniceus, sends backwards a very long, curved, rod-lilce process 

 to overhang, and thereby greatly increase the size of the orbit (PI. XLII. fig. 2). It 

 sends downwards a large antero-posteriorly flattened limb, the outer border of wliich 

 is produced still further downwards into a short rod-like spine which articulates with 

 the quadrato-jugal bar. The body of this ventral process of the lachrymal is perforated 

 by a large foramen for tlie passage of the lachrymal duct. The inner border of this 

 ventral process articulates with the antorbital plate. 



In Casuarms the laclirymal differs from that of iJroma'ns in the greater relative 

 shortness of its external orbital process, which is scarcely longer than the internal. A 

 further point of diff"erence lies in the fact that the external orbital process passes 

 insensibly forwards and downwards into a laterally compressed plate, which, after 

 forming the boundary caudad of the posterior narial aperture, turns sharply backwards, 

 and becomes the antero-posteriorly compressed ventral process bounding the lachrymo- 

 nasal fossa as described in Dro)nceus. From this it differs in that the laminated portion 

 is continued downwards to the level of the quadrato-jugal bar, instead of stopping short 

 of this, and sending downwards thereto a spine from its outer border. The foramen for 

 the lachrymal duct is smaller than in Broinceiis. Internally it articulates witli the 

 antorbital plate. 



In Rhea the lachrymal resembles that of Bromceus. The supra-orbital process is 

 large. The lachrynio-nasal process is also antero-posteriorly compressed. The foramen 



