512 



STRUCTURE AND CLASSIFICATION OF BIRDS 



bone to the outer part of a nasal and to the naso-maxillary 

 of the Dinornithidse (see below). 



There is a well-developed, though thin and curved, 

 ectethmoid lamina, which joins the maxillo-palatine below 

 and the descending process of the lacrymal above. This has 

 been also stated to be absent. 



Rhea has seventeen cervical vertebra. The atlas is 

 notched, as in Struthio, but not so widely. In the shoulder 

 girdle the procoracoid is short, but is continued down to the 

 articulations of the coracoid by the menibrana coracoidea, 

 of which, in a specimen of Rhea macrorhynclia before me, a 



FIG. 242. STERNUM OF Rhea (AFTER MIVART). 

 cc, coracoid grooves ; ca, anterior lateral process ; /, keel i ? ) : It; posterior lateral process. 



portion is ossified as a thin spicule of bone shutting in the 

 foramen coracoideum. The sternum (see fig. 242) has a 

 median ventral prominence and two lateral thin rings of the 

 bone, which may be indications of foramina. Three (some- 

 times four) pairs of ribs reach the sternum. The pelvis 

 (fig. 243) has a small pectineal process. The pubes join 

 the ischia posteriorly, and anteriorly an interobturator pro- 

 cess, of which there are faint indications in Struthio, unite 

 the two bones. Posteriorly the ilia are attached to the 

 ischia. 



