BEV. W. HTNCKS ON CT&NUS PASSMOBI. 3 



examined proved that tlie specimens were from the first rightly 

 referred, and that, in fact, Mr. Yarrell's figure belongs to our 

 new species, not to the true C. huccinator as we understand it. 

 Comparing my sternum of Oygnus Passmori with Mr. Yarrell's 

 figure and description, it appears that the bony protrusion at the 

 anterior extremity of the inner face of the sternum is somewhat 

 less solid and less compressed laterally in mine, and that the fold 

 of the trachea within the hollow carina does not advance so far in 

 mine as in Mr. Tarrell's, both which circumstances are explained 

 by his bird being the older ; but the resemblance is too close to 

 admit a doubt of specific identity. I proceed, then, to describe the 

 sternum and trachea of what I regard as the true G. huccinator. 

 In this, as in the preceding case, the trachea descends without 

 changing its course, passing between the branches of the furcula 

 until it reaches the level of the carina, when it bends backwards 

 and enters between the bony plates of the carina. Proceeding 

 backwards and inwards, it rises above the level of the inner face 

 of the sternum, making a wide bow, which is covered by the bone 

 of the inner surface of the posterior portion of the sternum, as 

 represented in Mr. Yarrell's figure of the sternum of Cygnus Be- 

 wicMi (Transactions, vol. xvi. tab. 25. fig. 3) and in the accom- 

 panying drawings. But in C. huccinator the rise of the trachea from 

 the carina is more sudden, so that there are very slight traces of 

 a rising over its course until the commencement of the bow, 

 which is also larger than it is represented in C. BewicTcii : and the 

 returning fold of the trachea, instead of immediately passing out 

 as in C. BewicTcii, rises into a protuberance at the anterior ex- 

 tremity of the sternum, of the same kind with that of C. Passmori ; 

 but, instead of rising only, as in that species, to the level of the ver- 

 tical bone of the sternum, it rises an inch above it, with a decided 

 inclination to the right side, looking forward. Within this extra- 

 ordinary protuberance the trachea bends round, and, as it descends, 

 comes out under the arch of the furcula, the exterior portion being 

 manifestly enlarged, and having much broader rings, contracting 

 again laterally as it approaches the bone of divarication (see 

 fig. 8). The bronchise had been destroyed in both specimens of 

 the sternum and trachea of G. huccinator before they came into 

 my hands ; but they are described as abruptly much swollen 

 close to the bone of divarication, with the tubes shorter than in 

 Gygnus Passmori. The figure of the sternum itself also seems 

 to differ in the two species, the angular enlargements at each side 

 of the anterior arch on the interior surface being much more dis- 



