Archive image from page 39 of The Cyathaspididae; a family of. The Cyathaspididae; a family of Silurian and Devonian jawless vertebrates cyathaspididaefa135deni Year: 1964 orp —-'''' -ds - vs Fig. 105. Sagittal sections through anterior part of shield of Protopteraspis vogti (from Heintz, 1962). A, as preserved; B, as restored. ds, dorsal shield; mxb, maxillary brim; orp, oral plates; ort, oral tooth lamella; ro, rostrum; vs, ventral shield. pared their position to that of lungfishes. Stensio (1958, fig. 193) showed similarly placed notches in Poraspis pompeckji, but he inter- preted the
Archive image from page 39 of The Cyathaspididae; a family of. The Cyathaspididae; a family of Silurian and Devonian jawless vertebrates cyathaspididaefa135deni Year: 1964 orp —-'''' -ds - vs Fig. 105. Sagittal sections through anterior part of shield of Protopteraspis vogti (from Heintz, 1962). A, as preserved; B, as restored. ds, dorsal shield; mxb, maxillary brim; orp, oral plates; ort, oral tooth lamella; ro, rostrum; vs, ventral shield. pared their position to that of lungfishes. Stensio (1958, fig. 193) showed similarly placed notches in Poraspis pompeckji, but he inter- preted them as probably housing tentacles. Nostrils in the position of these notches would be bounded medially by oral-lateral or pos- sibly lateral plates. Openings in this position are not apparent in any articulated pteraspids or cyathaspids, and so their existence is doubtful. If external nostrils were absent, the olfactory organs pre- sumably opened into the anterior part of the buccal cavity. In Stensio's latest reconstruction (1958, figs. 190, 200), the nasal cap- sules are unpaired, lie just in front of the pineal organ, and are con- nected with the exterior by the hypothetical naso-hypophysial duct and prenasal sinus. Brain.—The pineal organ, usually indicated by the pineal macula externally (fig. 91,A, pm), and by a corresponding pit on the inner side of the dorsal shield (figs. 106, 132,A, 151,A, 155, 156, pfo), is the most important landmark in the anterior part of the brain. It is logical to assume that it lay, as in lampreys, at the anterior end of the diencephalon, and that the telencephalon lay antero-ventrally
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