638 GEOLOGICAL SURVEY OF THE TERRITORIES. 
are concave-elliptical surfaces, with their major axes parallel to the 
median line. The anterior ones are the more circular. 
The zygapophysial processes, to assist in the intimate proximity of 
these vertebra, are short and thick. The anterior ones look upwards 
and inwards, the reverse being the case with the posterior series, which 
latter develop pointed spines that overlap above, each in its turn, on 
either side, the vertebra next behind, at the base of the common neural 
spine. The longest of these processes are found anteriorly; they, gradu- 
ally disappear aS we near the sacrum. 
The first dorsal hypapophysis consists of three plates, arising from 
the centrum of the vertebra separately, and arranged as shown in Fig. 
38. Onthe second dorsal we find only a single quadrate plate in the 
median plane, directed forwards. It occupies a position at the anterior 
margin of the vertebra, but is produced posteriorly as a low, thin lamina 
of bone, along the remainder of the centrum mesial to the raised and 
posterior margin. The third vertebra takes it up in this form, and it 
is thus passed along the series, constituting a continuous hypapophysial 
ridge, intersected by the expanded anterior and posterior borders of the 
centra. . 
The articular surfaces among the bodies retain their usual characters. 
They extend into the ridge just described. The centra of the dorsal 
vertebra are somewhat compressed in a slightly increasing degree from 
before backwards; each lateral and anterior margin supplies a nearly 
circular parapophysis for the pleurapophysial capitula, while at points 
on the posterior margins in the same plane we find the major share of 
the notch, which in coaptation of the segments constitutes the subeireu- 
lar foramina for the exit of the dorsal nerves. 
There is a free plewrapophysis for each dorsal vertebra, but the first is 
not always connected with the sternum by a sternal rib, as already de- 
fined; it sometimes has all the characteristics of a movable cervical rib; 
again, when it connects with the sternum, its hzemapophysis articulates 
rather high on the costal border (Pl. IV, Fig. 22). It may or may not 
bear an epipleural appendage. 
The vertebral ribs of this Lark articulate, as usual, by tubereula and 
capitula, with the dorsals, meeting par- and di-apophyses in the ordinary 
manner. ‘The necks of the ribs in the middle of the series are the long- 
est, and often we find among the ultimate ones a slight projection be- 
yond the tubercle, that is received in a corresponding notch at the outer 
border of the diapophysis it meets. There is but little difference in the 
width of these flat bones; perhaps the auterior ones have rather the 
advantage in this respect. Minute apertures, to allow the air to enter 
their bodies, are observed in the usual localities. 
The laterally viewed curve of a dorsal rib is barely sigmoidal; viewed 
from in front it approaches a portion of the curve of an are of an ellipse. 
A ridge continuous with the neck is carried down the inner aspect of 
each bone, to gradually disappear near its middle. The lower extremi- 
ties of these ribs are slightly enlarged, to afford space for articulation 
with the sternal ribs; the surface is convex. 
The epipleural appendages of the dorsal pleurapophyses are conflu- 
ent with the posterior edges of the bones, and situated below their mid- 
dles. Occasionally the one in the middle of the series has sufficient 
length to overlap two ribs; in young birds of this species they are much 
Shorter, and the best-developed ones show an angle on their interior 
borders just after leaving the rib, as if they had left that bone with the 
original intention of proceeding downwards and backwards at a gentle 
