Osteological Studies of the Sub-Family Ardeincc. 
15 
meet the baso-pterygoid apophysis when the latter is present, in 
birds where this articulation occurs. Other Herons have the 
pterygoids constructed in precisely the same way. I fail, however, 
to find the pneumatic foramina in the Night Herons in the same 
locality as described above for A. hcrodias , but no doubt a larger 
series of specimens would 'show it, as the same projection exists 
in the pterygoid. 
In the Blue Heron the basisphenoidal region is elongated and 
develops a median keel which merges into the inferior surface of 
the rostrum just beneath the pterygoidal heads. The Eustachian 
tubes are guarded only by a thin over-arcliing lamella of bone. 
As in Sula and other fqrrns the basitemporal area is much con¬ 
tracted, while in the dried skull the tympanic cavity is so exposed 
that no little care is requisite at first to place the parts. The 
foramina for the pneumagastric, glossopharyngeal, hypoglossal 
nerves and internal carotid artery, relatively occupy their usual 
sites, as seen elsewhere in this class. 
Upon this inferior view of the skull we really see the under 
side of the occipital condyle, as its form and articular surface ap¬ 
pears only in full view when the skull is looked at directly from 
behind. 
This direct posterior view of a bird’s skull is a very instruct¬ 
ive one, a fact that was thoroughly appreciated by so talented an 
anatomist as Garrod, who presented us with a number of them 
among his valued papers, as for instance where he makes the 
telling comparisons among the skulls of Chauna dei biana, Chlot- 
phaga viagellanica , and Mitua tuberosa (P. Z. S., 1876, pp. 1S9- 
200). 
Such a view of the skull of this Heron is shown in Figure 5, 
where the broad crotaphyte fossae are seen, separated from each 
other in the median line above by an exceedingly narrow space. 
The supra-occipital region stands prominently out, partially over¬ 
hanging the sub-circular foramen magnum. Regularly uniform, 
with the notch upwards, the large occipital condyle is here better 
seen, jutting directly backwards from its lower margin. Beneath 
and in the middle region, the pterygoids and the four caiinations 
of the palatines come into view. These aie flanked on either side 
by the ponderous quadrates, which latter show the large pneu¬ 
matic foramen in each, leading into theii hollow interiors. 
Above, on either side, the sphenotic process can be seen, 
