46 THE CLASSIFICATION OF BIRDS 



PASSERIFORMES. 



23. TKOCHILI. 24. PASSEEES. 



The Passeriformes embrace two Orders the Trochili * and the 

 Passeres very nearly related to each other, and possibly not 

 sufficiently distinct to be placed in different Orders. 



The Passeres have a broad and truncated vomer. The Trochili 

 also have a broad and truncated vomer, but the truncation is not 

 complete; it leaves a long mesial spine. The Trochili only contain 

 one family ; but the Passeres may be divided into four families. 



The Passeridce and the Menuridce differ from the Tyrannidce 

 and the Eurylamidce in having the intrinsic muscles of the syrinx 

 fixed to the ends (not the middle) of the bronchial semi-rings. 

 The Eurylcemidce differ from the other three families in having 

 the flexor perforans digitorum connected by a vinculum with the 

 flexor longus hallucis. The Menuridce differ from the other three 

 families in having no interclavicular process. 



The Passeridce are not only the most numerous but also the 

 most cosmopolitan of all birds. The Trocliilidce are distributed 

 over the tropical and subtropical parts of the New World. The 

 range of the Tyrannidce is rather more extended climatically, and 

 in the Old World extends to various parts of the tropics. The 

 Eurylccmidce are locally distributed in tropical Asia ; whilst the 

 Menuridce are confined to Australia. 



* In spite of anything that may have been written to the contrary, there can 

 be no doubt that the deep plantar tendons of the Trochilidce are normal ; that is 

 to say, the flexor perforans digitorum leads to the three front digits and does not 

 lead to the hallux. The flexor longus hallucis is a more erratic tendon in the 

 TrochilidcR, as elsewhere. In some species it is united by a vinculum to the 

 other tendon, but in others no trace of this has been found. In addition to the 

 excellent dissections which were made for me by Miss Lister, Professor Stewart, 

 and Mr. Bourne, of the Eoyal College of Surgeons, have been kind enough to 

 make others which confirm in every particular those already made and figured. 

 The two tendons appear to coalesce before the slip leaves for the hallux, but 

 shortly afterwards the coalesced tendon appears to bifurcate ; the outer branch 

 very soon again bifurcates, leading to the third and fourth digits, whilst the 

 inner one leads to the second digit. The two tendons are, however, very im- 

 perfectly coalesced, and with a little pulling may be separated, when it is at 

 once obvious that the flexor perforans digitorum leads to the second, third, and 

 fourth digits, whilst the flexor longus hallucis leads to all four digits. An almost 

 exact replica of this arrangement is to be found in the Osprey. 



