SHUFELDT.] OSTEOLOGY OF THE SPEOTYTO. 603 
vertebraa much more solid appearance, which in reality it possesses above 
that attained by any of its fellows. This bony lamina is reduced in the 
fourth vertebra to a mere “‘interzygapophysial bar” connecting the pro- 
cesses, while in the next succeeding one or two vertebre it occurs only 
on the prezygapophyses more as a tubercle, being directed backwards, 
then disappearing entirely, is to be found again only on a few of the 
last cervicals as an ill defined knob, still retaining its original position- 
The diapophyses at first project nearly at right angles from their re. 
spective centra, then approach the median line by being directed more 
backward near the centre of the cervical division of the column, and on 
nearing the dorsals again gradually protrude more and more directly 
outward. The prezygapophyses of the ninth cervical support well- 
marked anapophysial tubercles, which are feebly developed also on a 
vertebra or two both above and below the ninth. The joints between 
the bodies of the cervicals of this Owl are upon the same plan as those 
found throughout the class; the anterior facet being concave from 
side to side, convex from above downwards, the reverse being the case 
with the posterior facets, and when articulated fitting accurately into 
each other. The pleurapophysial elements, well marked in all the cervi- 
cals after passing the axis, become in the thirteenth vertebra a free 
cervical rib, about three millimetres in length, without neck or true 
head, being merely suspended on either side from the diapophysis of 
the vertebra, and freely movable on its exceedingly minute articulating 
facet. 
Attached to the last cervical we find the second pair of free pleura 
pophyses, about two-thirds as long as the first pair of dorsals or true 
ribs of the thorax, terminating in pointed extremities and articulating 
with the vertebra by both capitula and tubercula, the former on ellipti-_ 
cal facets, placed vertically on either side of the centrum at the anterior — 
margin of the neural canal, and the latter on rounded facets beneath 
the diapophyses. The tubercle on one of these ribs is nearly as long as 
the neck; at the junction on the posterior side is found a pneumatic 
foramen of considerable size. These ribs are more or less flattened 
above from before backwards, being convex anteriorly, concave poste- 
riorly, becoming rounded below. From the third to the ninth vertebra, 
inclusive, appear beneath the vertical canal anteriorly well-developed 
styliform parapophysial processes, directed backwards and downwards. 
They are best marked on the segments of the middle of the neck. There 
is no instance in this bird of these processes being produced so far 
backwards as to touch the next vertebra below; their tips, as a rule, 
about overhanging the middle of the centrum of the vertebra to which 
they belong. We have found in specimens of Bubo virginianus the 
parapophyses of the fourth vertebra overlapping and touching the fifth 
for a millimetre or more. The third and fourth cervicals have, beneath 
in the median line posteriorly, strongly developed hypapophyses, quad- 
rate in form, @ process that exhibits itself on the fifth vertebra, ante- 
riorly, merely as a small tubercle. On the sixth this tubercle has disap- 
peared, and has been supplanted by two others that are now found just 
within the periphery of the anterior facet of the centrum on the para- 
pophysis of each side, beneath and inclined toward each other. These 
processes, now a double hypapophysis apparently developed from the par- 
apophyses, continue to increasein size and inclination towards each other 
on the next three vertebra, so that on the ninth, where they last appear, 
they nearly form a closed canal. The passage between them is intended 
for the carotids, to which they afford protection. The hypapophysis of 
the tenth, eleventh, and twelfth vertebre is single, large, quadrate, and 
