3HUFELDT. | OSTEOLOGY OF THE SPEOTYTO. 605 
fore or behind them, and thus constitute an additional aid to the rigid. 
ity of the back, as it does in other species of this family and in muny 
other birds. The centra increase in depth beneath the neural canal the 
nearer they are to the sacrum. In the first dorsal the body measures 
about one millimetre, the vertical diameter of the canal being three; in 
the last dorsal it equals the diameter of the canal. The interarticular 
facets are in the vertical plane, with their coneavities and convexities op- 
posed to each other, as they were described when speaking of the last cer- 
vicalvertebre. Thebodies are aboutof a length, constricted at their mid- 
dles and expanding towards their extremities. The first two dorsals each 
bear in the median line, beneath, au hypapophysial process of consider- 
able size, affording abundant surface for attachment of some of the muscles 
oftheneck. The process of the first dorsal has one common trunk, with a 
compressed midprong and two lateral and pointed subprocesses. (See 
Pl. II, Fig. 5.) The second dorsal possesses a single long hypapophysis, 
quadrate in form, dipping into the chest further than the first. There 
is not a trace on the remaining dorsals of this appendix. Parapophysial 
processes, so prominent in nearly all the cervicals, afford in the dorsal 
vertebre simply articulating facets for the capitula of the pleurapophy- 
ses situated just within the anterior margin of the neural canal of each 
centrum, never extending to the vertebre beyond, forming the demi-facet 
of andranatomia. Immediately above these facets, on either side, may be 
noticed a group of pneumatic foramina of various sizes and shapes, and 
again, anterior to these foramina, the rim of the body of the vertebra for 
a limited distance becomes sharply concave, being opposite to a like con- 
cavity in the next vertebra, the two, when opposed and articulated, form- 
ing the oval foramen for the exit of the dorsal nerves. Elliptical artic- 
ulating facets for the tubercula of the pleurapophyses, looking down. . 
wards and outwards, are seen on the inferior ends of the diapophyses 
with a midridge running from each facet to the base of the process, to 
be expanded and lost on the sides of the centra. As there are five dor- 
sal vertebra, so are there five pleurapophyses articulating with them and 
with the hemapophyses below. Each rib is attached to a single verte- 
bra, as shown while speaking of the dorsals. The necks of these ribs 
become more elongated the nearer they are to the pelvic extremity of 
the body, the first possessing the shortest. This is exactly reversed in 
regard to the pedicles bearing the tubercula, being the longest in the 
first pleurapophysis and shortest in the last. This contraction of the — 
pedicles is progressively compensated for by the lengthening of the cor- 
responding and respective diapophyses of the vertebra to which they 
belong. Viewing the ribs from the front, in the skeleton, the curve they 
present resembles the quadrant of a shortened ellipse, the vertex of the 
major axis being situated at the base of the neural spines; viewed lat- 
erally, the curve is sigmoidal, thougha much elongated and shallow one, 
with the hemapophysial extremity looking forwards and the facet of 
the tubercle backwards. The first rib is the shortest and generally, 
though not always, the broadest; the last being the longest and most 
slender, the intermediate ones regularly increasing in length and dimin- 
ishing in breadth from the first to the last. In form, the ribs of this 
Owl are flattened from side to side, widest in the upper thirds, narrowest 
at their middles, and club-shaped at their lower extremities, where they 
articulate with the sternal ribs hy shallow facets. On theinner surfaces 
we find the necks produced upon the bodies as ridges, running near their 
anterior margins and becoming lost at about the junction of the upper 
and middle thirds in the body of the rib. Pneumatic foramina, from 
two to three in number and of considerable size, are found just within 
