58 THE ORDERS. 



To the second group all the existing birds can, as far as we know 

 be referred. It can be divided into : 



I. Ratuve, having the sternum or breast bone devoid of a 

 keel. 

 II. Carinat*, having the sternum with a keel. 



We need not concern ourselves with the subdivisions of the Ratitas, 

 as no birds without a keel to their breast bone have been recognised 

 as belonging to our national avifauna, and we doubt if any enthusiast 

 would be bold enough to add one to the British List on the strength 

 if having shot it on British ground. 



Familiar as the breast bone may be, on the dinner table and else- 

 where, it is perhaps as well to give a sketch in order that there may 

 , be no mistake. Here is one seen in section 

 and in three-quarter view, in which the 

 keel- is duly, though somewhat microscopi- 

 cally, noted. Of the Ratitae the most 

 familiar example is the Ostrich, which has 

 a breast bone as flat as a raft, raft being 

 ratis in Latin and thus being responsible 

 for the derivation. 

 In the Carinatse, then, the sternum possesses a keel, and ossifies 

 from a median centre in that keel, as well as from lateral paired 

 centres. The long axes of the adjacent parts of the scapula and 

 coracoid make an acute or a slightly obtuse angle, and are never, even 

 approximately, identical or parallel. The scapula always has a 

 distinct acromion and the coracoid a clavicular process. The vomer 

 is comparatively small, and allows the pterygoids and palatines to 

 articulate directly with the basisphenoidal rostrum. 



The CarinatEe, so-called from the Latin carina, a keel, are classified 

 according to their palatal bones ; or, to be more precise — we will 

 explain the technical terms immediately we have cleared the 

 way — into : 



I. Having the vomer broad behind, and interposing between 

 the pterygoids, the palatines, and the basisphenoidal 

 rostrum. 

 II. Having the vomer narrow behind ; the pterygoids and 

 palatines articulating largely with the basisphenoidal 

 rostrum. 

 To the first of these no British birds belong, the type of the group 

 being the Tinamous. Of the second there are three divisions ; and 

 representatives of each of these are to be found in our list. But, to 

 proceed in proper sequence. The group having the vomer narrow 

 behind can be divided into : 



I. Having the maxillo-palatines free. 

 II. Having the maxillo-palatines united. 

 Dealing first with those having the free maxillo-palatines we find 

 them further classified into : 



I. Having the vomer pointed in front — Schizognathse. 

 II. Having the vomer truncated in front. 

 The Schizognathous birds we will tabulate presently, and to save the 

 repetition of some very long words, we will here be satisfied with 



