STUDIES OE THE MA.CROCHIEES . 
381 
into four distinct muscles, but rather to resemble that of the Fly- 
catchers, although nothing certain can be stated on this point.” 
My own investigations upon other species than T. colubris go 
towards establishing in the main this admirable description of a 
very painstaking anatomist, for whom I have always entertained 
the highest regard both for his character and his work. It is 
needless to add that such a trachea, the counterpart of which is 
seen only iu the Spoonbill, is sufficiently far removed from the 
form it assumes in the Cypseli to satisfy the most sceptical as 
to any affinity on that point ! In Swifts it does bifurcate “ at the 
usual place ; ” it possesses but two pairs of muscles (the lateral 
ones, and those that go to the sternum), and in all other points 
is widely and fundamentally at variance with the windpipe and 
bronchi of the Trochiii. 
Careful as MacGfillivray’s account is, however, he neglected 
to mention one very important difference, so far as these parts 
are concerned in the birds under consideration, and that is, the 
Trochiii constitute one of those rare groups which lack the pair 
of sterno-tracheales muscles ; 1 carefully searched for them in 
several species of Humming-birds, but failed to find them, and 
am quite convinced they do not exist. 
If the reader will kindly turn to figure 33 of Plate XXIII. 
illustrating this memoir, he will find my drawing of the trachea 
of a Humming-bird, and in figure 35 the position it occupies in 
the thorax and neck with respect to the other organs. 
Indeed, in figures 35 and 36 I have drawn the bodies of a 
Humming-bird and a Swift, after having carefully removed the 
pectoral muscles aud sternum, iu order to show this very thing. 
A glance at these two figures will be sufficient to satisfy any one 
as to the remarkable difference they present. In the Humming- 
bird, we are struck at once by the position of the trachea ; the 
direct course of the left carotid, the enormous heart , and the fact 
that the low position of the liver conceals from our sight all the 
other viscera harboured in the abdominal cavity. Here, as in 
most birds, the right lobe of the liver is the larger of the two, 
which in the Humming-bird, as we see, curls round the apex of the 
heart (more so in T, platycercus), modelling itself to that extre- 
mity of it. Still more at variance, as compared with the Swift, 
is the digestive tract of a Humming-bird, for, so far as I am fami- 
liar with the morphology of the group, in none of them do I know 
of a species which possesses, as compared with the size of its 
intestines, so exceedingly small a stomach 1 This organ, together 
29* 
