140 
GENERAL OBNITHOLOGY. 
anchylosis of their t)odies and processes, but also, in many cases, by ossifications of the 
tendons of muscles of the back, and coossifications of these with the vertebrae, like a set of 
splints, till the consolidation of the thoracic is only surpassed by that of tlie pelvic region of the 
spine. Dorsal vertebrae also usually differ a good deal from most cervicals in having shorter 
bodies, laterally compressed, producing a ridge which runs along their middle line below ; in 
lacking a vertebrarterial canal ; in having on each side two articular facets, — one on the body 
and the other on the transverse process, for the head and shoulder of a rib. They are further 
distinguished, usually, by having large spinous processes, in the form of high, long, thin, 
squarish plates, often or usually anchylosed together. Their transverse processes are also 
very prominent laterally, thin and horizontal, and often anchylosed. More or fewer dorsals 
may bear large hypapophyses ; which, as in the loon, may bifurcate at their ends into two 
flaring plates. Such processes continue a similar series from the neck, and are in relation to 
the advantageous action of the muscles {rectus colli anticus and longus colli) by which the 
neck is made to straighten out from the lower curve of its sigmoid flexure. 
The " Sacrum " of a Bird (figs. 57, and 60) is commonly considered to be that large 
solid mass of numerous anchylosed vertebrae in the region of the pelvis, covered in by, and 
fused more or less completely with, the principal bones of the 
pelvis, or haunch-bones (ilia). But in this consolidation of an 
extremely variable number (averaging perhaps twelve, but run- 
ning up to at least twenty, eleven to thirteen being usual) 
of bones are included vertebrae which in other animals belong 
to several different sets — dorsal, lumbar, sacral proper, and 
coccygeal or caudal. We have just seen that one or two, even 
three, vertebrae, which are dorsal according to the definition 
agreed upon, may enter into the composition of the sacrum,'^ 
being firmly anchylosed there\^dth, and their long ribs issuing 
out from underneath the ilia, as shown in fig. 56, sr. Next 
comes one bone, or a series of several (two to five or more) 
bones, anchylosed together by their bodies and spinous proc- 
esses, and also anchylosed with the ilia by means of stout lateral 
bars of bone sent transversely outward on either side from their 
respective centra to abut against the ilia. These cross-bars 
correspond in general form and position with the transverse 
process of the last true rib-bearing dorsal, — that process against 
which the shoulder of any developed rib abuts ; they are variously 
considered to be, to represent, or to include rudimentary ribs; 
and such difference of view may be warranted by the state of the 
parts in difi'erent birds. However this may be, the bones just 
described are lumbar vertebrae (Lat. lumhus, the loin ; where 
such vertebrae are situated in man and other mammals) ; which 
certainly possess abortive ribs in some cases. On successive 
lumbars the cross-bars, whatever their nature, commonly slip 
lower and lower downward (belly-ward) on the vertebral bodies, 
till the last ones are quite down to the level of the ventral 
aspect of the centrum ; these are also commonly the stoutest, 
most directly transverse, and most nearly horizontal of the series 
of processes, abutting against the ilia a little in advance of the 
socket of the thigh bone. This ends a series of consolidated 
"sacral" vertebrae which are termed collectively " dorso-lumbar," 
Pig. 57. — The " sacrum " of 
a young fowl, seen from below, 
nat. size; after Parker, dl, dor- 
solumbar series, whereof the first 
is dorsal proper, the next three 
are lumbar ; s, the sacral series 
proper, or true sacrum, consist- 
ing of five vertebrae ; c, the uro- 
sacral series, being those caudal 
vertebrae, six In number, which 
anchylose with one another and 
with the sacrum. 
