324 MR. W. K. PARKER ON THE OSTEOLOGY OF BAL/ANICEPS REX. 
The cervical vertebre of the Baleniceps are relatively stronger and shorter than 
those of the great Adjutant, whilst they form a remarkable contrast to those of the 
Heron—a bird which not only has more of these joints than its relations, but in which 
the individual vertebrz are exceedingly long and narrow. The difference between the 
structure of the neck in the typical Heron and in the Baleniceps is remarkably like 
what we see in the Mammalia, when we contrast the cervical vertebra of the Vicugna 
with those of some large Stag, such as the Wapiti, or the Sambur Deer. The large, 
broad, spoon-shaped jaws and the flat head of the Boat-bill require a shorter neck and 
individually shorter vertebra than those of the Heron with its long narrow cranium, 
and its narrow, straight, tapering, pointed mandibles. 
Yet in nothing but in the decrease of number and the shortening of each joint do 
the cervical vertebrae of Cancroma differ from those of Ardea; whilst all the change 
that has taken place between those of Baleniceps and Cancroma is that in the former 
two vertebree have been added, and the relative as well as real strength of each bone 
greatly increased. 
Atlas. (Pl. LXVI. figs. 1, 3, 4 at.) 
The atlas is small, as in all birds, and its ‘ proccelian’ cup for the articular condyle 
of the occipital bone is large in proportion. This cup is imperfect, a large crescentic 
piece being cut away, as it were, from the top, to make room for the ‘ odontoid’ pro- 
cess, which process, although ossified to the axis, in reality belongs to the atlas, being 
the internal or ‘ diaphysial’ part of its centrum. Behind where the upper edge of the 
cup is cut away, there are two small articular facets of a semi-elliptical shape for arti- 
culation with the sides of the tip of the odontoid process. In Baleniceps and its allies 
there are no foramina for the vertebral arteries on the sides of the atlas. The post-zyg- 
apophyses of the atlas send backwards a rather broad triangular process for muscular 
attachment: these are obsolete in Cancroma and the Small-headed Heron; but they 
are largest in the Adjutant, in which bird they divaricate outwards. The posterior 
articular surface of the centrum of the atlas is of the usual U-shape, and the inferior 
surface is marked in its latter half by one mesial and a pair of lateral tubercles. The 
upper concave aspect of the centrum is full of small pneumatic holes. 
Note.—In the Woodpecker and other arboreal birds, the cup of the atlas has a 
very perfect rim, but it is perforated below for the passage of the odontoid ligament ; 
here also the vertebral arteries are bridged over. In the young Emeu the lower or 
‘hypophysial’ part of the atlas is distinct from the neural arch as well as from its 
odontoid element. Query, does not this part of the Bird’s centrum answer to the 
marginal parapophyses of the abdominal vertebre of the Fish, as well as to the mesial 
hypapophyses of the Vertebrata generally ? 
It is not easy to draw a line between these processes or elements (which are so 
seldom autogenous), and to say where one begins and the other ends; at any rate the 
lateral processes of the base of the atlas are the homotypes of the parapophyses of the 
succeeding vertebra, whilst the mesial tubercle is a rudimentary ‘ hypapophysis.’ 
