Appendix. 69 



thicker, the eleventh still more evidently so, whilst the twelfth is as thick as any of the superior 

 rings. 



Anteriorly there are twenty-three of the lower tracheal rings, which are quite slender in 

 the niidtlle line, especially the three lowest ; and of these the twelve lowest (those split laterally) 

 are slender from one side to the other, whilst the upper eleven appear thick at their extreme 

 ends on account of the intrusion, for a short distance round the sides of the tracheal tube, of 

 the tliickening above recorded of their hinder parts, which diminishes rapidly in a spindle-poiiited 

 manner. 



The lowest tracheal ring is as slender as those just above it; and it is worthy of note 

 that the processus vocales rest upon the thickened second bronchial semi-ring as well as on the 

 first. These vocal processes cannot be detached from the sides of the trachea without injuring 

 it; and the sterno-tracheal muscles arise from their apices, to which are also attached thin muscular 

 sheets which extend up the windpipe laterally and a little posteriorly. 



Grallaria yuatemalensis. — In this species also the specialised syrinx does not cease abruptly 

 at its upper end, the superior rings of the trachea, which help to constitute it, gradually losing 

 their individual chai-acter. Figs. 2 and i, Plate VIII, represent the front and back view of the 

 organ, which is peculiarly shallow for its width, and involves but six of the lowermost tracheal 

 rings. These six are incomplete at their sides where they are in contact with the processus vocales, 

 which latter are small, flat, fusiform ossifications, pointed both at their ujjper and lower ends, and 

 just touch the upper of the two superior enlarged and ossified bronchial semi-rings, the remainder 

 of each bronchus being of the normal character. The last tracheal ring is incomplete in the 

 middle line in front, as well as at the sides, whilst behind it is thickened, and sends small down- 

 ward processes on each side of the middle line in such a manner as to develop a notch between 

 them. Figure 3 represents the left-side view of these structures, seen from the interior of the 

 organ, as well as the processus vocalis. From figure 2 it can be seen that the tracheal rin^s four, 

 five, and six fiom the bottom are not ossified at all in front, and that rings seven, eight, and 

 nine are only so at their sides, whilst ring ten, with those just above it, are extremely thin in 

 the middle. Posteriorly also, from figure i it can be inferred that the rings above the lowest 

 ones are very slender, becoming thicker by degrees above the sixth, which is the highest of those 

 constituting the voice-organ. 



With reference to the muscles, it may be stated that the lateral muscle of the trachea on 

 each side covers and joins the upper extremity of the 2^>'ocessus vocalis, turninw off to become the 

 musculus stemo-trachealis opposite the ring third from the end, and sending no continuation on 

 to act directly upon the bronchial semi-rings. 



Lipawjus cineraceus. — In this species the single specimen at my disposal has the lower part 

 of the windpipe considerably damaged by shot. Nevertheless, as one side is comparatively un- 

 injured, I have been able to make out the essential points in the structure of the syrinx, which 

 does not differ much from that of Pipra leucocilla, as represented by Miiller. The lowermost 

 rings of the trachea are not peculiar, each one being deep, and meeting, at its superior and inferior 

 margins, the rings above and below it. The first and second bronchial semi-rings resemble those 

 of the trachea in their flatness, depth, and approximation, the third being the first normal bronchial 

 ring. It, with those which follow, are slightly peculiar in that they are ossified throu"hout 



