Catalogue of the fossil fishes in the British Museum (Natural History) .. . small. Scales of caudal region,when present, numerous and rhomboidal. 160 HETEROSTRACI. Synopsis of Genera. I. Orbits enclosed in dorsal shield. Shield consisting of seven parts, fused in adult. Pteraspis (p. 160). II. Orbits forming lateral notches in dorsal shield. Shield consisting of a single plate Palcsaspis (p. 169). Shield consisting of four parts , Cyathaspis (p. 170). Genus PTERASPIS, Kner & Huxley. [R. Kner, Haidingers Naturw. Abhandlungen, vol. i. 1847, p. 165 ;emend. T. H. Huxley, Quart. Journ. Geol. Soc. v
Catalogue of the fossil fishes in the British Museum (Natural History) .. . small. Scales of caudal region,when present, numerous and rhomboidal. 160 HETEROSTRACI. Synopsis of Genera. I. Orbits enclosed in dorsal shield. Shield consisting of seven parts, fused in adult. Pteraspis (p. 160). II. Orbits forming lateral notches in dorsal shield. Shield consisting of a single plate Palcsaspis (p. 169). Shield consisting of four parts , Cyathaspis (p. 170). Genus PTERASPIS, Kner & Huxley. [R. Kner, Haidingers Naturw. Abhandlungen, vol. i. 1847, p. 165 ;emend. T. H. Huxley, Quart. Journ. Geol. Soc. vol. xvii. 1861,p. 166.] Syn. Palceoteuthis, F. Roerner, Palaeontogr. vol. iv. 1855, p. 72. Archceoteuthis, F. Roemer, in Bronns Leth. Geognostica, vol. i. 1855, p. , E. R. Lankester, Rep. Brit. Assoc. 1864 (1865), Trans. Sect. p. 58 (in part). Dorsal shield arrow-head-shaped, consisting of seven separatelycalcined portions :—a large central disc, with a triangular azygousrostral jplate anteriorly and a large median dorsal spine posteriorly ; Fig. Pteraspis rostrata (Ag.).—Dorsal shield restored, after Lankester. a pair of orbital plates, completely enclosing the orbit on either sideand partially inserted between the rostrum and central disc; and a PTERASPIDJE. 161 pair of postero-lateral cornua, each pierced with a large [? branchial]foramen. [? Pineal body occupying] a pit on the inferior aspect ofthe dorsal shield between the orbits. Yentral shield consisting ofa single convex plate ( Scaphaspis). Caudal region with smallrhomboidal scales, slightly overlapping, and ornamented with few,delicate, imbricating ridges, parallel to the overlapped anteriormargins. The generic name Pteraspis was originally applied by Kner to thesimpleshields named Cephalaspis hivisii and C. lloydii by Agassiz,in conjunction with similar fossils from Galicia, these being all re-garded as not pertaining to fishes, but most nearly paralleled by theinternal shell of the Cephalopod,
Size: 1027px × 2433px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorbritishmuseumnaturalh, bookcentury1800, bookdecade1880
