5S0 HABITS AND ANATOMICAL STRUCTURE 
which appears to be a continuation of the membrane lining 
the trachea ; but which is quite divided from the membrane 
forming the approximate sides of the bronchial tubes *. 
The bronchial tubes have slender cartilages, that do not 
extend more than two-thirds around their circumference, 
even at their upper extremity. The approximate side of 
each tube, as is usually the case in birds, consists of a thin 
membrane, which is named by Cuvier membrane tympani- 
Jhrme ; but in the Psophia it can scarcely deserve that ap- 
pellation, for, instead of uniting the trachea and bronchial 
tubes into continuous canals, as in other birds, the upper 
edge of the membrane forming the bronchial tubes is not 
continued to the end of the trachea, but allows an opening 
into each tube, sufficient to admit with ease a common 
probe, — by which a portion of the air passing from the 
trachea can find its way into the great air-cells, without 
previously passing through the lungs. The elasticity of the 
bronchial cartilages is sufficient to keep these openings so 
distended, that air at the same time passes into the lungs 
through the bronchial tubes : as may be seen in the pre- 
paration I have made of one of the birds. 
It seems probable, from a consideration of the structure 
of the organs of voice and respiration in the Trumpeter, 
that the living bird has the power of regulating, in some 
degree, the relative quantity of air which shall pass in either 
direction, by the action of the sterno-trachealis and upsilo- 
tracliealis muscles, aided by the contractility of a very mi- 
nute pair of muscles (represented in Fig. 1. Z>), arising 
from the lower rings of the trachea, and inserted into the 
* I may remark, that the whole lower larynx of the Trumpeter, with 
the exception of the apertures in the bronchial tubes, has a striking rescm- 
■fiance to the corresponding organs in the Whimbrel, Scolopnx j)htTopns, a 
specimen of which I dissected about the same time as the first Trumpeter. 
