1G4 



AMERICAN BITTEUN. 



the gullet. This arraii.neiiieiit can be better uiKlerstoud by ref'en ing tufig. ;>'>, where 1 have given a section, 

 life size, through the neck and thoracic muscles : n, neck : e e, thoracic vocal muscles ; c, c. uiiper larynx ; 

 t. tongue ; s, s, tongue nmscles. 



These obstructions, or valves, of the gullet are opened by drawing the tlmraeic muscle upward and side- 

 ways and by drawing the larynx downward and backward. This latter named operation is accomplished by 

 the aid of a retractor which has its origin on the lower portion of the lai-ynx. and then extemling downward, 

 adheres to the lower portion of the oesophagul muscle. See fig- oi 

 and 36, h. 



Nor does this complicated arrangement for producing sound end 

 here; lying in the lower mamlible, on either aide, adhering to the jaws 

 just beneath the nostrils, are two muscles. These mandibular muscles 

 are about 1.20 long, and each gradually becomes enlarged toward the 

 anterior portion until it comes in contact with its fellow opposite. See 

 fig. 30, b. where a lifc-sizeil figure of the interior of the terminal two 

 thirds of the lower mandible is given ; beneath these muscles, which 

 also ])lay the part of valves, is slipped the tongue, ib. g., and thus l)y 

 pressing upward crowds the muscles against the roof of the upi>er 

 mandible, completely obstructing the passage from the entrance of the 

 gullet, to the tip of the bill. 



This mandibular valve can be seen in section, in fig. 3^, B, where a 

 figure twice life size is given; t, upper mandilile; f, bone of same; .J, J, 

 lower mandible ; o, o, mandibular muscle, beneath which is the tongue. 



The nasal opening in the interior of the upper portion of the 

 mouth is peculiar and seems to indicate that the air is taken into the 

 gullet through the nostrils. The anterior nasal opening is closed as in 

 many species of birds, with a valve sliown in fig. 38, where is given a, 

 figure twice life size. One side is longer than the other, and at the 

 base, that is, nearest the gullet, is a concavity, j, into which the 

 convexity in the opposite side fits. A, is the opening, and w, the hinge muscles, 

 angle. Between this valve and the posterior, permanently open, nasal 

 entrance is a space that is closed : fig. 30, B, where a figure of the upper 



portion of the mouth of the Bittern, half life size, is given ; z, is the anterior valvular opening, closed ; v, 

 the permanently open posterior entrance that comes within the mouth of the gullet, the lower edge of which 

 is brought up against the intervening closed space, ib. x, thus preventing the escape of the air. The external 

 nostrils, fig. 33, are furnished with large coverings which act as valves; a life size view of one of these is 

 given at fig. 33, D. 



Fig. 35. End view of tongue and 

 vocal muscles in throat of American 

 Bittern, life size;n, neck; e,e, thoracic 

 nmscles ; t, tongue ; s. s, tongue 

 muscles ; c, c, maxillary vocal 



llG. 30. Illustratmg vocal muscles, mandibles, etc., of American and Least Bittern. A, cr, 

 tongue ; a, upper larynx ; n, wind pipe ; h, maxillary vocal muscle of American Bittern. B, inside of lower 

 mandible of Am. Bittern: v, permanently open nasal orifice ; x, closed space; z, anterior valvular opening. 

 C, mside upper_ mandible, life size. Am. Bittern ; b, mandibular vocal muscles ; g, tongue. D, inside of upper 

 mandible, life size, Least Bittern ; e, nasal opening. 



