1909. | OF THE PASSERINE BIRD ARACHNOTHERA MAGNA. 529 
in those birds it is better marked as a rule, and carried further 
backward, having the supraoccipital prominence standing between 
the furrows after the common one separates posteriorly. This 
character is also a feature of the skull in Acanthorhynchus among 
the Meliphagide and probably other honey-sucking species which 
possess tongues, the thyro-hyals of which curl over on top 
of the skull and are extensible. Cinnyris chalybeus is another 
example. 
In A. magna the frontal region is rather broad between the 
peripheries of the orbits, and still broader in front of the 
lacrymals, where the cranio-facial line is quite distinct. The 
superior mandible seen from above is smooth and the culmen 
rounded. This part of the skull can best be studied on side view. 
Here it will be noted tbat it is gently decurved for its entire 
length, which is just double of that of the rest of the skull. It 
tapers very gradually to the sharp apex, while its tomia possess 
clean cutting-edges. The rather large elliptical external narial 
apertures open far back just beyond the cranio-facial hinge, or 
rather line (see Plate), and they have no true bony partition 
separating them mesially. This is entirely different from what 
we find in the Humming-birds, where these mandibular narial 
openings are long and slit-like. They are very large, and occupy 
a mid-position on the bill in such species as Prosthemadera nove- 
hollandie, Acanthogenys rufigularis, and other Meliphagide, forms 
with shorter and stouter mandibles. 
We find that A. magna has a capacious orbital cavity, with its 
osseous walls fairly entire. The pars plana is large and thick 
and faintly shows above its union with the lacrymal. Its outer 
margin, forming a part of the periphery of the orbit, is, like the 
rest of this margin round to the postfrontal, sharp and defined. 
On its orbital side the pars plana is markedly concave, but 
convex in front, while below it meets the anterior end of the 
quadrato-jugal bar. The latter is almost of hair-like proportions, 
very delicate, and straight. This is also the case in other species 
of the Nectariniide, some few Meliphagide, and in the Trochilide. 
Nearly all of these birds have a vacuity of a greater or less size 
in the interorbital septum, and the openings for nerves on the 
anterior wall of the brain-case, within the orbit, as those for the 
first pair, are large, and in A. longirostris merge with the foramen 
in the interorbital septum. The optic foramen, however, is 
generally distinct, and in such a species as Climacteris scandens, 
and probably its near allies, there exists no deficiency in the 
orbital septum, while the brain-case above exhibits a very large 
opening into the orbit. 
Owing to the extreme slenderness of the osseous structures at 
the roof of the mouth posteriorly, the floor of the orbital cavity 
is distinctly deficient in bone, and this is the case with all the 
species in this genus, as well as in some of the related forms. On 
the lateral aspect of the cranium we find the postfrontal process 
