File:Bulletin (1971-) (20235271248).jpg

Title: Bulletin
Identifier: bulletin7477sout (find matches)
Year: 1971- (1970s)
Authors: Southern California Academy of Sciences
Subjects: Science; Natural history; Natural history
Publisher: Los Angeles, Calif. : The Academy
Contributing Library: New York Botanical Garden, LuEsther T. Mertz Library
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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1976 CRANIAL OSTEOLOGY OF A SURFPERCH 33 plates which form a major portion of the lateral walls of the cranial cavity. They are bordered medially by the parietals, posteriorly by the ex- occipitals, ventrally by the prootics, and anteriorly by the sphenotics. Well-developed ridges formed by the posterior continuation of the sphenotic projections run longitudinally along the entire length of the supratemporals, forming a shelf be- tween the temporal groove above and the dilator groove below. The lateral margin of this shelf bears a longitudinal fold for the passage of the in- fraorbital latero-sensory canal. The intercalaries are small, irregular, scalelike bones located at the posterior tips of the supra- temporal ridges, where they articulate with the lower arms of the posttemporals. The cone-shaped epiotics form the posterior dorsal margin of the neurocranium. They are bor- dered anteriorly by the parietals, medially by the supraoccipital, and ventrally by the exoccipitals. They articulate with the upper arm of the post- temporals. The elongate supraoccipital bears a well-devel- oped medial crest. It forms the dorsalmost portion of the posterior cranial roof, and is bordered anteriorly by the frontals and laterally by the parietals. The supraoccipital does not reach the foramen magnum, but is bordered posteroventrally by the epiotics. The exoccipitals are nearly rectangular. Pos- teriorly the two bones meet and form the upper portion of the foramen magnum. They are bor- dered posterodorsally by the epiotics, antero- dorsally by the parietals, anteriorly by the supra- temporals and prootics, and ventrally by the basioccipital. The posterior ends articulate with the first vertebra. The crescent-shaped posttemporals articulate with the rest of the neurocranium by means of an upper arm that joins with the cpiotic, and a lower arm that joins with the intercalary. In addition the posttemporals bear an anteriorly directed pro- jection which connects by means of a ligament with the posteriorly directed projection arising from the parietals. Posteriorly the posttemporals articiikile with the supracleithra, thereby providing a connection between the cranium and the pectoral girdle. Basicnmud region.—The rectangular basioc- cipital lies below the exoccipitals, and forms the lower portion of the foramen magnum. A deep longitudinal groove runs along its entire ventral surface. The basioccipital is bordered anteriorly
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L 10 MM Figure 5. Dorsal aspect of hyobranchial region: BB, basibranchial; BH, basihyal; CB, ceratobranchial; CH, ceratohyal: EB, epibranchial: EH. epihyal: HB. hypobranchial; HHD, dorsal hypohyal; HHV, ventral hypohyal; IH, interhyal; PB, pharyngobranchial. by the parasphenoid, while its posterior end bears surfaces for articulation with the first vertebra. The elongate, rod-shaped, parasphenoid (Fig. 3) forms the central lower margin of the neuro- cranium. Anteriorly it fuses with the posterodorsal surface of the prevomer. Anterodorsally it forms the lower medial margin of the orbital chamber. Posterodorsally it is ankylosed with the prootics by means of two wing-like ascending processes. Posteriorly it connects with the basioccipital. Ventrally the expanded pharyngeal condyles (Fig. 4) provide articular surfaces for the third pair of pharyngobranchials. BRANCHIAL APPARATUS Hyobrancliial region.—The small, rod-shaped, intcrhyals (Fig. 5) are borne on the dorsal poste- rior surface of the epihyals. The dorsal end of each interhyal articulates with the symplectic bone. The epihyals are triangular, and connect loosely with the more elongate ceratohyals. Each epihyal bears two branchiostegal rays on its lower surface, while the ceratohyals bear four. The dorsal hypohyals connect firmly with the anlcrodorsal surface of the ceratohyals, while the ventral hypohyals connect with the anteroventral surface of ilic ecrainln.ils

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