STUDIES OF THE MACROCHCRES. 
327 
and offers the proportional amount of articulatory surface to the 
glenoid cavity. Its blade is narrow, rather long, of an equal 
width throughout, and compressed from above downwards. Pos- 
teriorly its extremity is obliquely truncate from within outwards, 
while the end itself is slightly curved in the same direction. 
Either coracoid is characterized by a very extensively expanded 
sternal extremity of a quadrilateral outline, and of no great thick- 
ness in the antero-posterior direction. The shaft of the bone 
above this dilated end is rather slender, subcylindrical, being 
compressed from before backwards, and is evidently hollow. Its 
summit is not conspicuously enlarged, though it is rather more 
tuberous than we find it in such a group, for instance, as the 
Passeres. The head is directed in the articulated skeleton upwards, 
forwards, and inwards. Its scapular process is not very wide, for 
the scapula projects over it a little, both mesially and to its outer 
side ; while in the former direction it stands between its superior 
articulating edge and the corresponding head of the clavicle, i. e. 
the scapula does. Air seems to gain access to the shafts of the 
coracoids, and perhaps to some extent to the extremities of these 
bones ; but, so far as I have been able to discover, neither the os 
furcula nor the scapulae possess any pneumaticity. 
Neither of these Trogons possess, upon either side, the little 
ossicle at the shoulder-joint known as the os liumero-scapulare , 
though it is just possible that it may in every case have been 
removed by accident during the preparation of the specimens. 
Of the Pelvis and the Coccygeal Vertebrae. — No marked differ- 
ences distinguish the pelves of these two species of Trogons. 
There is some general resemblance between the pelvis of T. mexi- 
canus and the bone as we find it in certain Caprimulgine birds, 
though when we come to the details in such a comparison the 
divergence is sufficiently marked. 
Viewing the pefvis of Trogon mexicanus from above, we observe 
that the preacetabular area is considerably more extensive than 
is the postacetabular (PI. XIX. fig. 14). The outline of this 
upper surface is somewhat quadrilateral, its average width being 
about equal to its average length. In this specimen there are no 
existing vacuities among the diapophyses of the sacral vertebrae. 
One or two extremely minute ones are found in these positions in 
the specimen of T. puella among the ultimate vertebrae. 
Marked lateral extension characterizes the transverse pro- 
cesses of the sacral vertebrae, more especially those three which 
