204 STRUCTURE AND CLASSIFICATION OF BIRDS 



There is no crop ; the gizzard is thin-walled and large ; the 

 proventriculus is zonary. 



The most remarkable matter concerning the osteology of 

 the trogons is the curious mistake which was originally made 

 as to the nature of the palate. HUXLEY, in his paper upon the 

 classification of birds, came to the conclusion, from a single 

 incomplete skull of Trogvn Heinwardti, that the skull was, 

 like its presumed allies, desmognathous. Later FORBES l was 

 able to show in five species that the maxillo-palatines were 

 not united across the middle line, but that they terminated 

 in a spongy expansion some way from each other. The end 

 of the vomer, is thin and filiform. The lacryrnal is somewhat 

 styliform, and reaches the jugal bar ; there appear to be no 

 ossified ectethmoids. The palatines of the trogons are 

 peculiar. Instead of being flat plates, as in Cor&cias, for ex- 

 ample, the outer portions of the bones are bent upwards, and 

 cling closely to the basis cranii. The tw r o palatines are, 

 moreover, fused posteriorly, and the pterygoids where they 

 articulate with them are expanded. They are holorhinal 

 with impervious nares. The trogons have fifteen cervical 

 vertebra. The atlas is perforated by the odontoid process ; 

 four or five ribs reach the sternum. The sternum has two 

 incisions behind, and the bifid spina externa. 



CORACIJE 



Definition. After-shaft present Muscle formula, AXY ; expansor 

 secundariorum present. Cseca generally present. Desmogna- 

 thous. 



The Coraciidse are entirely Old-World birds, chiefly 

 massed in the Ethiopian region, but extending as far as the 



1 ' Note on the Structure of the Palate in the Trogons,' P. Z. tf. 1881, 

 p. 83G. 



