390 MR. w. A. FORBES ON THE [May 4, 



a secondj though shallower, fenestra is formed between them and 

 the second and third pairs. The fifth semirings are slightly dilated 

 at their extremities, where they are in close proximity, before and 

 behind, with the first four pairs. The sixth and succeeding bron- 

 chial rings take on the ordinary character, being deeper than 

 those that precede them, and gradually becoming more complete, 

 till the fifteenth pair are nearly perfect. On one side, the left, in this 

 specimen, the eighth and ninth semirings are partially fused exter- 

 nally. 



The lateral muscles of the trachea, after the insertion of the sterno- 

 tracheales, become excessively thin, so that it is difficult to make 

 out accurately their exact extent. They apparently fan out, so as 

 to be nearly in contact with each other before and behind, and are 

 inserted onto the first bronchial semirings for the greater part (as 

 far as I can make out) of their lateral surface, the tips, however, 

 being quite free from muscular fibres. 



Philepitta is therefore perfectly ]\Iesomyodian, as Prof. Garrod 

 predicted would probably be the case '. 



There are thus three families of Mesomyodian Passeres in the 

 Old "World — the Pittida, the PhilepittidcB, and the Eurylcemidce. 

 All agree in the possession of a broncho-tracheal syrinx, in that 

 respect agreeing with the Cotingidce (including Rupicola), Pipridce, 

 and TyranmdcE of the New World, and differing from the Tracheo- 

 phone families, which are all, as is well known, American. Philepitta 

 differs in the details of its syrinx from all the other " Haploophone " 

 Passeres. In Pitta (cf. P.Z.S. 1876, pi. 53. figs 1-G) the bron- 

 chial semirings are much less modified, being nearly entirely simple 

 semirings ; the lateral muscle, too, is slender and not spread out as in 

 Philepitta. This fact, taken with others, as the scutellation of the 

 tarsi, osteology, &c., justifies, in my miud, the establishment, as has 

 been done by Sundevall under the name Paictidce, of a separate 

 family for the bird under consideration '. The Eiirylcpmidce differ 

 in their retention of a plantar vinculum {cf. Garrod, P.Z.S. 1877, 

 and supra, p. 382), as well as in the structure of their feet and 

 other points. In the form of their syrinx, however, they approach 

 Philepitta perhaps more nearly than any form yet described, though 

 in them too the lateral muscle remains slender and unexpanded. 

 The peculiarities of the Eurylcemidce, and especially their oft-spoken- 

 of retention of the plantar vinculum, are sufficient, I think, to justify 

 their forming a main division of Passeres by themselves, as suggested 

 by Prof. Garrod ^, which may be termed Desmodactyli in distinc- 

 tion from the others or Eleutherodactyli. Prof. Garrod's 

 arrangement of Passeres ^ may therefore be modified as follows : — 



^ Voice-organs of Passeres, p. 68. 



^ The general myology and vascular system of Philepitta are still, it must 

 be remembered, unknown, but are in all probability perfectly Passerine. 

 ^ Voice-organs of Passeres, p. 73 and P. Z. S. 1877, p 449. 

 * P. Z. S. 1876, p. .518. 



