In the Apteryx the ilia are longer and more concave superiorly, and the ilio-sacral prolon gation short ; and both are separated more distinctly from the opposite ones by the coalesced extremities of the sacral spines, forming an elongated ridge of bone down the rniddle, and separated from the ilia and ilio sacral pieces by distinct parallel sutures.
The ischia, in this bird, as well as in the fossil giganticDinornis, or wingless bird ofNew Holland, are not placed, as in the Cursores before mentioned, parallel with the ilia, but form an anteriorly retiring or reversed ischial angle of 140'; and they do not coalesce posteriorly, either with the pubes or the sacrum, but have free truncated extremities, presenting a great general resemblance to the pelvis of the Emu. The pubes are parallel to the ischia, and, like them, free and diver gent.
In the Natatores the pelvis is long and broad, and generally much expanded posteriorly by the divergence of the ischia and large sacro sciatic ossification, for the attachment of the powerful muscles used in swimming ; and the great intercotyloid distance gives to their gait its peculiar waddle (see fig. 104.). That of the Loons and Penguins, however, is remark ably contracted, long, and narrow, with little intercotyloid distance.
The usual number of sacral vertebrm is fourteen, as in the Swan ; the Grebe has thirteen, and the Duck fifteen, and the sea Swallow ten only. The sacrum is usually very broad ; but in the Penguin and Loon it is unusually narrow, and in the former it is united by ankylosis to the last dorsal vertebra. The cocc-yx is usually composed of eight pieces. The Goose and Pelican have but seven, and the Barnacle Goose nine. In Penguins it is strong, and assists in the support of the body in its usual vertical position. It is usually curved much dorsally, affording a larger pos terior pelvic outlet.
The ilia are moderately' long, and overlap the posterior ribs. In the Penouin they are said, by Wagner, not to be anCylosed to the sacrum, but connected only by ligamentous union • thus increasing its loose and waddling gait. 'The ischia are very long, diverg-ent, and largely expanded into a very broad sacro sciatic element, enclosing a small sacro-sciatic foramen. They are prolonged posteriorly into a sort of styliform process in the Auk and Puffin. The pubes are very long, slender, and divergent, and are expanded at the extremity, and curved inwards in the Swan, Diver, and Gannett. They. do not generally unite with
the isehia posteriorly ; but, in the Swan, Duck, and Pelican, the obturator foramina are com pleted by the union of these bones, and are small and elongated.
The Gallineo have large and strong pelves, in correspondence with their powerful legs, used chiefly for progression and scratching up their food.
The sacru»z is broad, and composed of from ten pieces, as in the Turkey, to fifteen in the Pheasant and coinmon Fowl. The coccyx has five pieces in the Pheasant and Turkey, and, in the latter, is said not to be perforated for the spinal chord. In the Pea cock there are eight pieces, and the terminal bone is a horizontal oval plate to support the radiating feathers. In the tailless Manx va riety of the common Fowl, the coccyx is borted into a single tubercular projection.
The ilia and ilio-sacral ossifications are broad, and the ischia long, divergent, and widely expanded posteriorly into a very broad sacro sciatic element, much hollowed out in the pelvic cavity, and enclosing a large foramen (see fig. 105. /). This is especially marked in the Crown Pigeon, Bu stard, Crested Curassow, and Guan. The pubes are long, and generally unite with the ischia to complete an elongated obturator hole (p). In the Dove, the pubes and ischia are united in their whole length, and the foramen is obliterated, while in the Crested Guan and Trumpeter it is subdivided into an anterior and posterior portion, as in the Ostrich and Rhea.
In the Grallatores the sacrum is broad, and composed of frorn ten to twelve pieces, but in the Oyster Catcher there are fifteen. In the Snipe the transverse processes are more or less separated. The coccyx is in seven or eight pieces.
The ilia and ischia are shorter and broader than in the Natatores, the former being placed more parallel to the spine, crossing it at about 165° ; and the latter forming an ilio ischial angle of 160°. The inter-cotyloid dis tance is very great, especially in the gigantic Crane, but in the Stork and Bittern the whole pelvis is smaller and more contracted. The pubes are long, diverging, and parallel to the ischia, especially strong in the Aptenodytes ; and enclosing often a large obturator foramen by coalescing with the ischia. In tbe Stork, Ibis, and Flamingo, however, there is no such union.