SHUFELDT.] OSTEOLOGY OF THE SPEOTYTO. gis) 
slightly overhanging frontals, or, more correctly, the minute surface ap- 
pearance of the prefrontal, for although it is not evident in the adult that 
that bone makes itself visible at this point, yet it may be demonstrated 
in Skulls of younger specimens. The culmen, as in other birds, is formed 
by the intermaxillary, which is here firmly united with the nasals, and 
the two in conjunction form the peripheries of the truly elliptical external 
nasal apertures or nostrils, the first bone bounding them anteriorly, 
while the latter completes their ares in the rear. These in the dry skull 
measure through their major axes seven millimetres, and through their 
minor ones barely five millimetres. They have a distinct ring raised 
around their circumference, which is wanting, however, where they 
nearest approach each other anteriorly atthe culmen. The plane of the 
nostril faces upwards, outwards, and forwards; the nostrils are com- 
pletely separated from one another by a vertical bony septum, developed 
from the intermaxilary, not a common occurrencein birds. They have, 
in addition, a concave bony floor, that rises behind into a posterior wall 
leaving really two semicircular openings just beneath the culmen, sepa- 
rated from each other by the vertical septum. The osseous mandibular 
tomium, also a part of the intermaxillary, is as sharp as when the bill is 
sheathed in its horny integument. The are is concave, and falls off 
rapidly as it approaches the tip of the beak. Occasionally, in very old 
birds, the ethmo-turbinal bones in the nasal passages may ossify. The 
nasals form here the sides of the bill, and are firmly anchylosed to the 
bones they meet, except the lacrymals. The movability of the fronto- 
mandibular artjculation is limited. The dry skull is extremely light and 
brittle, giving one the sensation in handling it that he might experience 
while examining an egg from which the contents had been removed. A 
line drawn from the tip of the upper mandible to the outermost point of 
one tympanic, around the are of the cranium to a similar point on the 
opposite side, and back to the point of departure, describes nearly the 
sector of a circle. The longest radius, which is in the median line, meas- 
ures four and one-half centimetres, the cord between the tympanics 
about three centimetres. 
The hyoid arch.—The hyoid arch is suspended from the base of the 
skull by its usual attachments. In this Owlit consists of but six very 
delicate little bones, involving five articulations. The tips of the up- 
turned posterior extremities are about opposite the lower borders of the 
temporal fosse, its two limbs diverging from each other at an angle equal 
to that made by the lower mandible. The cerato-hyals are rathcr large 
in comparison with the other bones. They are joined both anteriorly 
and posteriorly by bony bridges, forming a fenestra between them, to 
be filled in by a thin membrane. The amount of divergence they make 
- from each other is less than that made by the hypo-branchial elements 
of the thyro-hyals. Anteriorly, the bone connecting them supports a 
cartilaginous glosso-hyal, while the posterior connection presents for 
examination the usual smooth articulating surface that enters into the 
arthrodial joint it makes with the basi-hyal. The basi-hyal and uro- 
hyal are confluent, not a sign of the point of union remaining. The 
latter bone is continued a short distance posteriorly by a tip of cartilage. 
The anterior end of the basi-hyal is devoted to the articular surface for 
the bone connecting the cerato-hyals, forming the joint mentioned above. 
It is concave from above downwards, convex from side to side, the lower 
lip being the longer. It will be plainly seen that this combination grants 
to the tongue a movement in the vertical and horizontal planes. _The 
anterior articulating heads of the hypo-branechial elements of the thyro- 
hyals are opposite each other, each being received into the diminutive 
