524 MR. A. H. GARROD ON THE [JunC 5, 



rings are incomplete opposite the processus vocales (in other words, 

 at their sides), as they are in all the Tracheophonae ; and the lowest 

 is also broken, as it were, in the middle line behind. 



Posteriorly the lower nine are extremely slender; the tenth 

 (counting upwards) is somewhat 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 middle line, especially the lowest three ; 

 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 thickening above recorded of their 

 hinder parts, which diminishes rapidly in a spindle-pointed 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 pro- 

 cesses cannot be detached from the sides of the trachea without in- 

 juring 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. 



Grullaria guatemalensis. — In this species also the specialized 

 syrinx does not cease abruptly at its upper end, the superior rings of 

 the trachea, which help to constitute it, gradually losing their indi- 

 vidual character. Figs. 1 and 2 (Plate LIII.) 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 in- 

 complete at their sides where they are in contact with the processus 

 vocales, which latter are small, fiat, fusiform ossifications, pointed 

 both at their upper 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 lowermost 

 tracheal is incomplete in the middle line in front, as well as at the 

 sides, whilst behind it is thickened, and sends small downward 

 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, a being 

 the processus vocalis. From figure 1 it can be seen that the 

 tracheal rings four, five, and six from 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 2 it can be inferred 

 that the rings above the bottom ones are very slender, becoming 

 thicker by degrees above the sixth, which is the liighest 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 ex- 

 tremity of the ijrocessus vocalis, turning off to become the muscuhcs 

 sterno-ti-achealis opposite the ring third from the end, and sending 

 no continuation on to act directly upon the bronchial semi-rings. 



