ON THE ANATOMY OF THE EURYLJEMIDJE. 143 



on essentially the same plan, with some modifications. The trachea, ** z - s - 1880, 

 below the insertion of the extrinsic muscles (on the last ring but six), 

 appears to be somewhat laterally compressed and diminished in size. 

 In the specimen before me the last few tracheal rings are somewhat 

 irregular in their disposition, which may or may not be due to individual p. Z. S. 1880, 

 variation. The antepenultimate ring is apparently incomplete on the P* ^* 

 right side, or is at least exceedingly reduced (vide fig. 5). The penul- 

 timate ring is narrowed, and is closely apposed to the terminal ring 

 throughout except in front, where there is a well-marked subtriangular 

 fenestra. The last trachea! ring is produced downwards in front, but is 

 apparently incomplete on the left side in front ; so that there the penul- 

 timate ring is next to the first semiring, in consequence of this disposition. 

 The pessulus is a well-marked, forwardly-directed linear process, p. z. S. 1880, 

 formed only by the right half of the last tracheal ring, which is thus, like P- 386. 

 the antepenultimate, incomplete for a part of its course. The first 

 bronchial semirings are much thickened and strongly arched ; they are 

 nearly in contact in front in the middle line, and are separated by but a 

 narrow space from the last tracheal ring ; behind they become incurved 

 and thickened. The second bronchial semiring is the slenderest of all ; 

 it is shorter than the first or third, and slightly concave downwards. 

 There is the same pseudo-ring formed, apparently by accumulation of 

 tissue inside, between it and the first semiring as already described in 

 Eurylcemus, but it is not so apparent here. The third semiring is much 

 longer, being the longest of all the semirings, and in consequence pro- 

 jecting at both extremities. It is nearly straight, narrow, but not so 

 narrow as the second ring, dilated behind and tapering slightly towards 

 the front. The first, second, and third semirings of each side are nearly 

 in contact with each other before and behind. The fourth ring has 

 much the same shape as the third, but is slightly shorter, and more con- 

 cave upwards than that one. The intervals between the second and 

 third and third and fourth rings are somewhat deeper than are the rings 

 themselves. The fifth and succeeding rings take on the usual form of 

 bronchial semirings, gradually becoming more complete. As in Eury- 

 Icemus, the single intrinsic tracheal muscle, which is very slender, is 

 inserted slightly behind the middle of the first bronchial semiring. 



The Eurylsemidse are therefore, as is evident from this description, 

 Mesomyodian*, in that respect agreeing with most of the other " Formi- 

 carioid " Passeres of Wallace (Ibis, 1874, p. 406). It is probable that 

 the existence of an intrinsic muscle in the syrinx of Corydon sumatranus 

 escaped the notice of Johannes Miiller always supposing that in that 

 species the same essential form of syrinx occurs as in those above 

 described owing to its slenderness. They are not Tracheophone ; and 



* Garrod, P. Z. S. 1876, p. 517. 



