RUBY-THROATED HUMMING BIRD. 347 



The cesophagus, Fig. 2, is 1 inch 4 twelfths long, 1^ twelfth in width 

 at the top, but toward the lower part of the neck enlarged to If twelfth. 

 On entering the thorax, it contracts to ^ twelfth ; and the proventriculus 

 is 1^ twelfth. The stomach is extremely small, of a roundish or broad- 

 ly elliptical form, li twelfth in length, and 1 twelfth in breadth. The 

 proventricular glands form a complete belt, 2 twelfths in breadth. The 

 walls of the stomach are moderately muscular ; the epithelium dense, 

 with broad longitudinal rugae, four on one side, three on the other, and 

 of a pale red coloiu-. In the stomach were fragments of small coleop- 

 terous insects. The intestine is 2 inches 2 twelfths in length, from 

 l-A twelfth to I twelfth in width. It forms six curves, the duodenum 

 returning at the distance of 3 twelfths. There are no coeca. The 

 cloaca is very large and globular. 



The trachea. Fig. 1, is 9 twelfths long, being thus remarkably short, on 

 account of its bifurcating very high on the neck, for if it were to divide 

 at the usual place, or just anteriorly to the base of the heart, it would 

 be 4| twelfths longer. In this respect it diifers from that of all the 

 other birds examined, with the exception of the Roseate Spoonbill, Pla- 

 talea Ajaja, the trachea of which is in so far similar. The bronchi are 

 exactly I inch in length. Until the bifurcation, the trachea passes 

 along the right side, afterwards directly in front. There are 50 rmgs 

 to the fork ; and each bronchus has 34 rings. The breadth of the tra- 

 chea at the upper part is scarcely more than \ twelfth, and at the low- 

 er part considerably less. It is much flattened, and the rings are very 

 narrow, cartilaginous, and placed widely apart. The bronchial rings 

 are similar, and differ from those of most birds in being complete. The 

 two bronchi lie in contact for 2 twelfths at the upper part, being con- 

 nected by a common membrane. The lateral muscles are extremely 

 slender. The last ring of the trachea is four times the breadth of the 

 rest, and has on each side a large but not very prominent mass of mus- 

 cular fibres, inserted into the first bronchial ring. This mass does not 

 seem to be divisible into four distinct muscles, but rather to resemble 

 that of the Flycatchers, although nothing certain can be stated on this 

 point. 



The above particulars, it is to be hoped, will furnish, in so far, an 

 acceptable addition to the very little generally known of the struc- 

 ture of these diminutive birds ; and may afford some slight help to the 

 dry skin philosophers in " working out" their arrangements. 



