Archive image from page 918 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana03todd Year: 1847 OSSEOUS SYSTEM. (CoMP. ANAT.) (fig. 438, 1) united together. In die Siren and Proteus, however, the principal f'rontals are divided as in other Reptiles. In all Birds and Mammalia these bones become at an early period confused with the anterior and posterior frontals and ultimately with each other, so as to form but one piece, the os J'rmitis of man; nevertheless, even in the human foetus, they are separated by a suture which, in the lower Mammalia and also in
Archive image from page 918 of The cyclopædia of anatomy and. The cyclopædia of anatomy and physiology cyclopdiaofana03todd Year: 1847 OSSEOUS SYSTEM. (CoMP. ANAT.) (fig. 438, 1) united together. In die Siren and Proteus, however, the principal f'rontals are divided as in other Reptiles. In all Birds and Mammalia these bones become at an early period confused with the anterior and posterior frontals and ultimately with each other, so as to form but one piece, the os J'rmitis of man; nevertheless, even in the human foetus, they are separated by a suture which, in the lower Mammalia and also in the human subject, is not unfrequently persLstentto alate period of life. The anterior frontals (2) in the osseous Fishes bound the orbit anteriorly. Between these bones pass out the olfactory nerves, but they are not always distinctly recognisable, being occasionally permanently cariilaginous. In Reptiles these bones are generally distinct, but in Birds and Mammalia they coalesce with the preceding. The posterior frontals (4) form the posterior margin of the orbit, and are present in Fishes and the Reptilia, but in Birds and Mammifers they are no longer recognisable as distinct bones. The parietal bones (7) are placed behind the frontals; but these bones do not always touch each other, being separated, especially in Fishes, by the interposition of an azygos bone from w'hich projects the occipital spine, which is frequently, more especially in Fishes, of very good size: this impair bone, the interpurietul of some authors, is in reality the representative of the superior occipitals of Cuvier (supra- occipitals, Owen ;) (8) and in some Fishes, es- pecially in the Si/uri, where the parietals are totally wanting, their place is supplied by the enormous developement of this element of the skeleton. The external occipitals (9) contribute to form Fig 440. Section of the skull of Turtle ( Testttdo Mi/as). 829 the lateral portions of the occipital region of the skull, in conjuncti
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