THE ANATOMY OF BIRDS.— OSTEOLOGY. 149 
The Pubis (Lat. pubis. bone of the front of the human pelvis where the hair grows at 
puberty ; pl. pubes ; adj. pubic ; figs. 56, 60. 61 P), beginning at its share of the acetabular ring, 
is a long slender bone which runs along the lower border of the ischium, sometimes for a short 
distance only, often for the whole length of the ischium, and usually projecting behind ; more 
or less perfectly parallel with, applied to, or united with, the inferior ischiac border. When 
separate, a long deep fissure results; when united at the end, a long narrow foramen is 
formed ; when incompletely united in any part of its ischiae continuity, a fissure and a foramen, 
in the ostrich two foramina, result. All these conditions occur; in any ease, such ischio-pubic 
interval corresponds to the obturator foramen (fig. 56, 0; fig. 60. 0b) of human anatomy; it is 
greatest in Cretaceous birds and existing Ratite. The free ends of the pubes may be more or 
less expanded. In the ostrich only there is a pubie symphysis of the ends of the bones: in the 
same bird a separate ossicle, situated upon the lower border of the pubes, and called epipubic, 
is considered to represent a “‘ marsupial” bone (Garrod). In various birds, among them our 
ground cuckoo. Geococeyx californianus, the pubis projects a little forward, under the ace- 
tabulum: this prominence is the propubis. Separation of the pubes is supposed to be for 
amplification of the pelvic strait to facilitate the passage of the large chalky eggs birds lay. 
5. THE SKULL. 
The Skull of a Bird is a poem in bone— its architecture is the “‘ frozen music” of 
morphology ; in its mutely eloquent lines may be traced the rhythmic rhymes of the myriad 
ameebiform animals which constructed the noble edifice when they sang together.1 The poésy 
(wzoinots, poiesis, a making) of the subject has been translated with conspicuous zeal and success 
by Mr. W. K. Parker; its zodlogical moral has been similarly pointed by Professor Huxley ; 
and the young ornithologist who would not be hopelessly unfashionable must be able to whistle 
some bars of the eranial song — the pterygo-palatine bar at least. 
The rapid progress of ossification soon obliterates most of the original landmarks of the 
skull, fusing the distinct territories of bone in one great indistinguishable area. Thus the 
brain-box of almost any mature bird is apparently a single solid bone, and most parts of the 
jaw-scaffolding similarly run together. Aside from the bones of the tongue, which are collec- 
tively separate from those of the skull proper ; and of the compound lower jaw, which is freely 
articulated with the rest of the skull; only two or three other bones of the skull, as a rule, are 
permanently and perfectly free at both ends. These are the quadrate bones— the anvil-shaped 
pieces by which the lower jaw is slung te the skull: the pterygoids, articulating the palate with 
the quadrate ; and sometimes the vomer. Traces only of the bones of the face and jaws are 
usnally found; but even such vestiges disappear, as a role, from among the bones of the 
brain-box. It is necessary to any intelligent understanding of the construction of a bird’s skull, 
te learn somewhat of its mode of development in the embryonic stage; this being the only clue 
to the individual bones of which it is composed, and so to any correct idea of its morphology. 
One theory is, that the skull consists of four modified vertebra: and the principal bones have 
been named and described by some in terms indicating the elements of a theoretical vertebra. 
It is toe that the skull is segmented, or may be segmented off, like a chain of several 
vertebre ; that it continues the vertebral axis forward; that it has a basis cranii like a series of 
vertebral centrums, above which rises a segmented neural arch enclosing the great nervous 
mass. and below which depends a set of bones enclosing visceral parts like a hzemal arch. 
The hindmost cranial segment, the occipital bone, resembles a vertebra in many physical 
characters, and even in mode of development. But if the serial homology of the skull with 
i Bone-tissue chiefly consists of the aggregated skeletons of Osteamebe — a kind of uni-cellular protozoan 
animals which inhabit in myriads the bodies of nearly all the Vertebrata, possessing the faculty of feeding upon 
phosphate of lime and other earthy matters they find in the blood. and afterward excreting them in the form of 
multiradiate exoskeleions of their own, collectively forming the whole skeleton of their host. 
