SHUFELDT. OSTEOLOGY OF THE EREMOPHILA. 635 
wards, upwards, and then forwards, having the usual pneumatic foramen 
above and near their pointed extremities. The superior margin of the 
inferior maxilla starts at once from each articular surface, to rise by a 
moderate angle to the representative coronoids, a distance of 4 milli- 
metres; it then falls gradually to the rounded and anterior termination 
of the bone. It exhibits about its middle, on each side, a long but very 
low convexity, the corresponding shallow concavities being between them 
and the coronoidal elevations. The “ coronoids” are marked by deep 
groovelets with raised borders that extend forwards and downwards as 
far as the interangular vacuity. 
The inferior boundary of the bone, as already stated, rises on each 
side in the inferior articular surfaces, to ascend first for two-thirds of 
its extent on each ramus, then to fall at about an equal angle, to sweep 
round and form the anterior and curved termination in the dentary ele- 
ment. The median line on the dentary segment averages 5 centimetres, 
this portion of the bone being quite thick and concave above, convex 
below. The general surface, both inside and out, between the bounda- 
ries just defined, is in each case depressed, smooth, and translucent until 
we arrive at the solid dentary portion, where we find it marked by a 
row of minute pits. Of some dozen or more lower maxille before me, 
one of the most striking differences existing among them seems to be 
the variation in size of the interangular vacuity or foramen. This is 
elliptical in outline with the major axis of the ellipse in the long axis of 
the bone, and in some specimens squarely meet the raised ramal borders 
within, while in other individuals, even though the bone be larger, this 
foramen is markedly smaller. A large concavo-convex sesamoid is found 
between the tympanic and articular end on each side. The long axes of 
these bones are placed vertically, and their concave surfaces look for- 
wards. They are attached to the middle of the pointed articular pro- 
cesses behind by a delicate ligament, and above by the same means; by 
a somewhat broader attachment to the squamosals and tympanics, pos- 
teriorly. 
Spinal column, cervical portion—(Pl. IV, Figs. 22 and 35).—In making 
a study of the vertebral column of this Lark, the student will find that 
he will be materially assisted if he make use of an engraver’s eye-lens, 
or, better still, one of the low-power objectives of a good microscope, as 
some of the points for examination are rather minute, and are not so 
easily or satisfactorily demonstrated by the unarmed eye. The cervi- 
cal portion of the column is composed of thirteen vertebre ; these enjoy, 
from the atlantal throughout the entire series, a perfectly free move- 
ment among cach other by their several articular surfaces; and some 
form of the sigmoidal curve, characteristic of the bird-neck, is invaria- 
bly preserved during life and action. We find, too, the majority of the 
salient points pertaining to these segments described by ornithotomists, 
present, and strongly marked, and the chief functions of this jointed and 
bony isthmus well carried out—as affording protection for the myelon 
in its passage from the brain to the body below, and the vessels from 
their centre to the brain above. The neural canal, beginning in the 
atlas as a transverse ellipse, rapidly becomes circular, retaining this 
form throughout the tube, only to resume the elliptical again in the last 
two or three segments, where in the thirteenth it seems to be of a lar- 
ger calibre than at the cranial extremity, the ellipse still being placed 
transversely. 
The usual processes of ten of these vertebrae, the third to the twelfth, 
inclusive, afford protection to the vertebral artery and sympathetic 
nerve. By an apparent contraction of the parapophyses in the twelfth, 
