AMEi;i('AN lilTTEHX. 



105 



t;=: 



=^S3En]I!IQa 



g==:^IMjl]) 



FiG.t 



Bittern, 



i". Upper larvux of 

 life size ; upper fisr 



lower, lower si'ie 

 trachea ; s., tongue. 



larv 



Least 



side ; 



X : n, 



The Least Bittern, which has no need of such an arrangement, has no closed interspace between the two 

 nasal openings ; fig. ;)C, D, where is given a life size figure of the upper portion of the mouth of this species. 

 Over e is the anterior nasal opening, back of which, terminating at v, is the continuous posterior opening. 



In order to prevent the air from entering the windpipe, over which it passes to reach the guUetrthe 

 valves of the laryn.x are guarded with extra strong muscles which serve to close it. Compare fig. 30, A, 

 upper larynx of American Bittern, one half life size, with that of the Least Bittern, fig. 37, life size, upper 

 fig. side view, lower, as seen from telow : a, is the larynx with the muscles : g. tongue : n, trachea ; in all the 

 figures. The muscles of the larynx uf the larger species completely envelope the end of the trachea, whereas 

 in the smaller species, they merely cover the top and sides. 



Now having mentioned all the parts which make up the sound-producing organs. I will explain how they 

 are used, and how. by their aid. the booming of the Bittern is accoraidished. 



The air is evidently drawn into the gullet through the nostrils, as already explained, the bill being 

 closed during this process. The nostrils are closed when a portion of air is introduced sufficiently lar^re to swallow 

 and as this cannot escape, at least beyond the mandibular valve, fig. o-t, b, it is rea lily taken into the gullet, by 

 the simple act of gulping it djwn. The gullet, or oesophagul receptacle, 

 once full of air, during which operation, according to Mr. Torrey's 

 observations, the bird goes through some very strange contortions, our 

 musician is ready to utter his melodious song, or rather what answers 

 for such. 



The muscles that act upon the inflated gallet now compress it, the 

 valves at ib. o are opened and a bubble of air is admitted into the space 

 between the two sets of valves, indicated by the diverging lines at ib. d 

 being stopped at the mandibular muscles, ib, b. This is the first note, 

 " punk," a few seconds intervene and then the mouth is opened and the 

 air within it is released, or forced out by another bubble behind it, 

 comhig from the air reservoir, and we have two syllables, nearly 

 t)gether, " a-pog " the whole rendering, ti) my ears, being, ''punk-a-pog 

 that must be heard to be thoroughly understood. 



1 presume that there is considerable variation in the notes, as among other birds : that is, no two 

 Bitterns sing exactly alike. Varying distances will also cause the 

 notes to sound differently ; intervening objects like woods or hills will 

 obstruct the cadence and will cause it to vary ; then again, it is 

 difficult to find two persons who will exactly agree as to the 

 expression of bird notes, these sounds evidently not producing the same 

 impression upon one as upon another. 



With all this, however, I have little to do at present, and my 

 story of one of the most clumsy, ill-contrived arrangements for produ- 

 cing sound, that was ever possessed by any living animal, is nearly 

 told. I may say that no anatomist, even in his wildest dreams, would 

 «ver have conceived such a scheme I Indeed, the whole system is so 

 utterly without precedent among birds that have come under my 

 observation, that had I not been absolutely forced to believe that the 

 notes of the American Bittern were proiluced by this most sitigular 

 muscular arrangement, which evidently assume these peculiar func- 

 tions for a short time only, by having it exhibited to me so clearly that 

 there is no room for doubt, I never could have given it credit. 



When Mr. Torrey compared the voice of the Bittern to the sound 

 produced by a pump, his simile was not far from correct ; the vocal 

 apparatus of this bird is like a pump with two bo.xes. Mr. Torrey is 



rather inclined to think the sounds ai'o made by the act of inhaling air, but Professor Faxon more correctly 

 thinks the sounds are made by exhalation. 



with a i)eculiar watery intonation 



t 

 ]', 

 Fro. 38. Illustrating vocal organs 

 of American Bitteni. A, closing 

 valve anterior nasal o|iening : j, 

 upper side ; w, hinge. B. section 

 through bill;f, bone, of ujiper man- 

 diMe: J. .J, lower mandible ; o, 0, 

 maiidib\ilar muscles : t, tongue. 

 Both figures arc twice life size. 



