I) is a single knob, being formed almost wholly by the basi-occipital, while the lateral occipitals (often perversely called exoccipitals) take but little share in it.
Parker.) bo, Basi-occipital.
Later on fused with, a pair of membrane bones, the basi-temporals, homologous in part with the parasphenoid of lower vertebrates.
Rbs, Rostrum of basi-sphenoid.
The circular space on each side of the basi-temporal (bt.) is the opening of the anterior tympanic recess.
B.br, Basi-branchial, or urohyal, answering to the rest of the basibranchial series.
Genera: (a) Ore supero; basi se affigens: Actinia, Ascidia.
The cleido-mastoid generally arises from the basi-occipital, and the pectoralis major is connected with the latissimus dorsi.
The basi-hyal is remarkable for the long, median, pointed, compressed " glossohyal " process, which it sends forward from its anterior border into the base of the tongue.
The bones which bear the two occipital condyles have given rise to much discussion, and the definition given by Huxley in the previous edition - "two occipital condyles, the basi-occipital region of the skull either very incompletely or not at all ossified" - requires revision.
Some authors have held that the bone on which the occipital condyles have been found most developed in some labyrinthodonts (2) represents a large basi-occipital bearing two knobs for the articulation with the first vertebra, whilst the skull of the batrachians of the present day has lost the basi-occipital, and the condyles are furnished by the exoccipitals.
On the other hand, some reptiles have the occipital condyle divided into two and produced either by the basi-occipital or by the exoccipitals.
Woodward (3) to show that, in that form at any rate, the condyles are really exoccipital, although they are separated by a narrow basi-occipital.
The fact remains, however, that some if not all of the stegocephalous batrachians have an ossified basi-occipital.