THE ANATOMY OF BIIWS.— OSTEOLOGY. 149 



The Pubis (Lat. piibis, l)nrie of the fmnt uf tlie human pelvis where the hair grows at 

 puberty ; id. puhea ; adj. pubic ; figs. 50, 00, 01 P), beginuing at its share of the acetabular ring, 

 is a long slender bone wliich runs along the lower borchn- of tlie iscliiam, .sdinetimes for a short 

 ilistauco only, often for the whole length of the iscliium. and usually projecting behind ; more 

 or less perfectly parallel with, applied to, or united with, the inferior ischjac border. When 

 separate, a long deep fissure re.sults ; when united at the end, a long narrow foramen is 

 formed ; when incompletely united in any part of its ischiac continuity, a fissure and a foramen, 

 in the ostrich two foramina, result. All tliese conditions rjccur ; in any case, such ischio-pubic 

 interval corresponds to the obturator foramen (fig. 50, o; fig. 00, oh) of human anatomy ; it is 

 greatest in Cretaceous birds and existing liatitcc. The free ends of the pube.s may be more or 

 less expanded. In the ostrich only there is a pubic symphysis of the ends (if thi' biines ; in tlie 

 same bird a separate ossicle, situated upon the lower border of the pubes, and called epipiibic. 

 is considered to represent a " marsupial " bone (Garrod). In various birds, among them our 

 ground cuclioo, Geococcyx calif ornianus , the pubis projects a little forward, under the ace- 

 tabulum : this prominence is tlie propiibis. 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 HKULL. 



The Skull of a Bird is a poem in bone — its architecture is the "frozen music" of 

 morphology; in its mutely eloquent lines maybe traced the rhythmic rhymes of the myriad 

 amoebiform animals which constructed the noble edifice when they sang logethei'.^ The poesy 

 {nolrja-is, pioiesis, a making) of the subject has been translated with conspicuous zeal and success 

 by Mr. W. K. Parker ; its zoological mcjral 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 cranial song — the pterygo-palatine bar at least. 



The rapid progress of ossification soon obliterates most of the <iriginal 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 to the skull ; the pterygoids, articulating the palate with 

 the quadrate ; and sometimes the vomer. Traces <-inly of the bones of the face and jaws are 

 usually found ; but even such vestiges disappear, as a rule, from among the bones of the 

 brain-box. It is necessary to any intelligent understanding of the construction of a bird's skull, 

 to 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 vertebrae ; and the principal bones have 

 been named and described by some in terms indicating the elements of a theoretical vertebra. 

 It is true that the skull is segmented, or may be segmented off, like a chain of several 

 vertebrae; 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 hiemal arch. 

 The hindmost cranial segment, the occijiital bone, resembles a vertebra in many physical 

 characters, and even in mode of development. But if the serial homology of the skull with 



1 Bone-tissue cbiefly consists of tlie aggregated skeletons of OsteamtxbfE — a kinrt of uni-cellular protozoan 

 animals which inhabit in myriads the bodies of nearly all the Verfcbrata, possessing the faculty of feeding upuii 

 phosphate of lime and other earthy matters they lind in the blood, and afterward excreting them in the form of 

 multiradiate exoskeletons of their own, collectively forming the whole skeleton of their host. 



