1909.] OF THE PASSERINE BIRD ARACHNOTHERA MAGNA. 531 
especially at the base of the skull, in this genus of birds are 
notably small, to the very limits of minuteness. This includes 
the articulation of the skull with the spinal column, the quad- 
rato-jugal articulation, those with the pterygoids, and to some 
extent others. 
These last-mentioned bones are very slender, straight, and 
rather short, presenting nothing peculiar in their articulations 
with the quadrates and palatines. They do not appear to be in 
contact with each other in the middle line, though they do 
articulate with the sphenoidal rostrum. 
The postpalatine portion of either palatine is a delicate scroll 
of bone that articulates mesially with its fellow of the opposite 
side beneath the presphenoid, while the prepalatine portions are 
well apart, straight, and here reduced to a degree of slenderness 
rarely met with in birds of this size. A vomer is well-developed, 
spatulate in outline, and compressed throughont in the vertical 
direction. It is firmly codssified with a palatine upon either side. 
Each mawillo-palatine is reduced to the extreme in the matter of 
delicacy of structure, being but feebly developed. 
Coming to the mandible it is to be observed that it has the 
long V-shaped pattern, with a curvature for its anterior two- 
thirds corresponding to the curvature of the upper jaw, while its 
posterior third is somewhat flexed upon the anterior part of the 
bone (see Plate). The rami are very slender and very narrow 
from above downward, the structure upon the whole impressing 
one with its feebleness. A. magna has the length of the 
symphysial portion about equal to the posterior moiety of the 
bone; in A. longirostris it is considerably longer, and in this 
species, too, the curvature is greater and, if anything, the bone 
still weaker. Inferiorly, the “symphysis is smooth, and roundly 
convex transversely ; the tomia for this part being sharp. A 
small ‘‘ramal vacuity” is present in the mandibles of both these 
species, and the free ramal extremities are more or less pneumatic. 
There is at each end a small blunt postangular process, otherwise 
these ends are practically truncated and concaved behind. The 
usual inturned angular processes are present, each having at its 
tip or apex the pneumatic foramen found there in so many of the 
Class. The coronoid processesare aborted. In A. longirostris the 
mandible is 4°8 cm, long and only 2 mm. deep at its deepest 
part, about opposite the ramal vacuity. 
When normally articulated, the superior and inferior mandibles 
in the skull of Arachnothera ave in contact for their entire 
lengths. I find nothing to note especially in regard to the 
intrinsic ossicles of the internal ear, the siphoniwm, or the 
sclerotals of the eye. All are exceedingly passerine in character, 
For a representative of this group, however, the hyoid arches 
in this species are remarkable. Not only is the glossohyal 
greatly elongated to meet the requirements of the feeding-habits 
of the bird, but the thyrohyals are similarly produced. The 
