392 Prof. T. J. Parker. On the Development of [Feb. 23, 



Fig. 2. 



Yentral Yiew. - 



The united olfactory capsules consist of (a) the xnesethmoid, pass- 

 ing in front into the pre-nasal cartilage ; (b) the lateral ethmoidal 

 plates ; and (c) the turbinals. 



The mesethmoid forms in its posterior half a vertical plate, with a 

 thickened lower rim ; its posterior border is vertical, and forms the 

 front boundary of the pituitary fossa ; the posterior portion of its dorsal 

 border (cr. gall.) is concave, from before backwards, and has exactly the 

 relations of the crista galli of a Mammal. Passing forwards from the 

 crista galli, the mesethmoid reaches the surface of the skull, where, 

 with the adjacent portions of the lateral ethmoids, it forms a . 

 lozenge-shaped area between the posterior ends of the nasals. Cephalad 

 of this it gradually narrows in the vertical direction, finally becoming 

 in the anterior portion of the beak a mere rod, the pre-nasal cartilage 

 or basi-trabecular. There is now no trace of the parietal fenestra men- 

 tioned by W> K. Parker on the authority of Blanchard (" Ostrich Skull," 

 p. 173). 



In the lateral ethmoidal plates of this bird no clear distinction 



