176 STRUCTURE AND CLASSIFICATION OF BIRDS 



in the sense of Huxley ; the two maxillo-palatines, dilated 

 at their ends, conae absolutely into contact under the vomer, 

 the middle part of which they completely cover. In Guis- 

 calus versicolor the same arrangement occurs, the maxillo- 

 palatines being extraordinarily slender before they dilate to 

 overlap each other and to cover the vomer. 



As to the rest of the skeleton, Corvultur albicollis may 

 serve as a type. There are fourteen cervical vertehrce ; un- 

 impaired hypapophyses extend from the tenth to the first 

 dorsal. Five ribs reach the sternum, to the keel of which 

 the furcula is joined. 



The most salient variations from this plan are shown by 

 many genera in which the furcula does not join the keel of 

 the sternum, by Gorcorax, in which six ribs articulate with 

 the sternum, and above all by Gymnorhina, where there is 

 a catapophysial canal, beginning with the seventh and 

 ending with the tenth vertebra. In this and other forms 

 the hypapophyses of the last cervical and the first dorsal 

 vertebrse are reinforced by strong lateral catapophyses. 



In the table on the ' opposite page are some intestinal 

 measurements in inches. The most noteworthy fact in the 

 anatomy of the alimentary tract is the absence of the gizzard 

 in certain tanagers.' 



In almost all Passeres ^ the flexor hallucis is absolutely 

 independent of the flexor communis, there being no vinculum 

 at all. 



These characters are — adding to them those used in the 

 diagnosis of the family — the only ones that are universal, or 

 nearly so, among the Passeres. There are, however, a number 

 of anatomical features in which the passerines show differ- 

 ences among themselves. The most abnormal Passeres on 



' C£. FoKBES, ' On the Structure of the Stomach in certain Genera of 

 Tanagere,' P. Z. S. 1880, p. 143, who quotes Lund's earlier (1829) paper on the 

 same matter. 



'' For myology of passerines see, in addition to Gaeeod, .Klemm, ' Zur 

 Muskulatur der Eaben,' Zeitschr. f. d. ges. Naturv). xxiii. p. 107 ; Shufeldt, 

 T?ie Anatomy of the Baven, London, 1890 ; C. L. Nitzsoh, ' Ueber die Familie 

 d. Passerinen,' Zeitschr. f. d. ges. Nat. xix. p. 389 ; C. B. Uleich, ' Zur 

 Charaoteristik d. Muskulatur d. Passerinen,' ibid. xlv. p. 28. 



