Osteologiccil Studies of the Subfamily Ardciuce. 3 
Nycticorax. In the Great Blue Heron the head of the scapula 
• 
is compressed from above, downwards, and much expanded in a 
transverse direction. Mesially it curls up a little to preserve the 
contour of the “tendinal canal,” while on the opposite side, it 
supports an oblique, elliptical articular facet, constituting one- 
third of the glenoid cavity. 
Among the Herons the furcula, or the united clavicles, is a 
very interesting bone in one or two particulars. 
In figures 11 and 12 I present two views of this part of the pec¬ 
toral arch, taken from a specimen in my own collection of A. liero- 
dias , it being the same individual from which all the drawings 
were made which illustrate this form. I would do this, even if a 
hundred skeletons of the same species were at my command, as it 
is better in many respects. One of the chief reasons is that each 
skeleton, even among birds, has its own individuality and ought 
to furnish all the figures if possible in any type monographed. 
The head of the clavicle in this Heron is tuberous, rather thick¬ 
ened, and evenly rounded off at its end. When articulated with 
the other bones of the arch, its superior border, quite close to this 
extremity, rests against the under side of the projecting summit 
of the mesial aspect of the coracoid. The rounded end of the 
furcula, from this point, reaches back a sufficient distance to 
barely escape touching the mesial and up-curled side of the sca¬ 
pular head, thus to all intents closing the tendinal canal by long 
walls ; its complete closure is really effected by the short ligament 
that holds these two bones in situ at this, their nearest point of 
approach. In some birds, as for instance certain diurnal Rap- 
tores, the canal is closed by the head of the furcula reaching 
the tip of the clavicular process of the coracoid. From the head 
of the bone to the hypocleidium a gradual reduction in size takes 
place, while the lateral compression is sustained throughout, at 
any rate until within a short distance from the latter part. 
Now the hypocleidium of the clavicles in Ardca herodias , as 
in other herons, consists of both an inferior and a superior process 
(Fi gs. 11 and 12), both being in the saline line. In our present 
subject the upper one is the larger of the two, while their common 
surface anteriorly is smooth and flat. Behind, it is rounded and 
marked by a longitudinal raised line. This latter feature in 
Nycticorax is raised to the rank of a well developed crest, and 
