1877.] ANATOMY OF PASSERINE BIRDS. 525 



Lipaugus cineraceus. — In this species the single specimen at my 

 disposal, which Mr. Edward Bartlett has most kindly given me, has 

 the lower part of the windpipe considerably damaged by shot. Never- 

 theless, as one side is comparatively uninjured, 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 ap- 

 proximation, the third being the first normal bronchial ring. It, 

 with those which follow, are slightly peculiar in that they are ossified 

 throughout, except in a small part, equal to about one sixth the 

 breadth of each semi-ring, one third distant from their anterior ends, 

 where they retain their primitive cartilaginous structure {vide Plate 

 LIII. figs. 6 and 7). 



The lateral muscle of the trachea is of considerable breadth, being 

 most developed anteriorly, those of the opposite sides coming nearly 

 into; contact in the middle line in front. Opposite the tracheal ring 

 seventh from the bottom, the small sterno-trachealis is differentiated 

 off from the posterior portion of this muscle, by far its larger anterior 

 part continuing downwards to become the intrinsic muscle of the 

 syrinx, which ceases at its insertion into the anterior half of the 

 third bronchial semi-ring. It exhibits no tendency to split into two 

 as in Pipra leucocilla. 



It may be mentioned that the second bronchial semi-ring is some- 

 what expanded at its ends, intruding more into the membranous 

 completion of the bronchial tube than do those which follow it. The 

 damaged condition of my specimen makes it impossible to determine 

 whether the antero-posterior bar, which is situated at the point of 

 bifurcation of the trachea, is formed by the last tracheal ring, or by 

 the completion and junction of the fi'rst bronchial rings of either 

 side. I am inclined to think it depends on the latter of these 

 conditions. 



Chiromachceris manacus, according to the description given by 

 Miiller. agrees exactly with this species, as far as its syrinx is con- 

 cerned. 



Heteropelma verce-pacis. — It is Mr. Salvin whom I have to thank 

 for a specimen of this species, as well as the next to be described, in 

 spirit. Its voice-organ is most simple. The single, broad lateral 

 muscle of each side of the trachea continues down to the middle of 

 the second bronchial semi-ring, which is scarcely different from those 

 below it either in bulk or appearance ; and the one above it resembles 

 it. There is, however, a considerable interval between it and the 

 third, whilst it almost touches the first. None of the lowermost 

 tracheal rings are peculiar in any way. 



Hadrostomus aglaicB is a bird in which the calibre of the lower 

 end of the trachea is very inconsiderable, and the syrinx is corre- 

 spondingly difficult to investigate. The tracheal rings are not modi- 

 ' Loc. cit. plate iv. figs. 9-11. 



