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Show 1896.1 FISHES 0E THE FAMILY GOXOEHYNCHIDiF. 503 cranium is seen from above, but the only clearly distinguishable remains are those of the great pair of frontals (Jr.). Some characteristic portions of the small mouth are observable forwards below; one of the maxillae (mx.), a dentary (d.), and apparently a fractured articulo-angular element (ag.) being distinct. The bone (x) above the maxilla may perhaps be part of the large preorbital cheek-plate seen in Gonorhynchus (fig. 5). The right operculum (op.) and suboperculum (s.op.) are displaced upwards above the head, and the last-mentioned bone exhibits the four deep clefts in its hinder border. Bemains probably of four large brancbio-stegal rays (br.) occur below the head just in front of tbe rather obscure pectoral arch. The total number of vertebrae cannot be definitely ascertained, but seems to be between 50 and 60. Tbe centra resemble those of the American fish, though a little shorter in proportion to their depth: and the state of preservation of one specimen (Brit. Mus. no. P. 3884) suggests that each centrum was pierced mesially by the notochord. The delicate ribs are borne by stout processes from the centra, as noted bv Agassiz, and as well shown in the specimen of which the head has been described. The neural spines are expanded in the anterior part of the abdominal region,. as also shown in the same specimen and indicated by Agassiz in fig. 3 of his plate representing the species. The extremity of the vertebral column is formed precisely as described above in N. osculus, the lowermost expanded haemal spine at tbe base of the caudal fin being distinctly supported by the hinder border of the penultimate centrum; this, however, must be displaced forwards, for both the penultimate and the antepenultimate centrum bears its own hasmal arch, comparatively stout but not expanded. The fins appear to resemble those of N. osculus, but there are only eleven supports in the dorsal (clearly shown in Brit. Mus. no. 43436), the foremost with a wing-shaped expansion indicating its composite character. It is difficult to count the rays themselves, the two halves of each being so loosely apposed that in crushing they frequently slip one behind the other. The scales are comparatively thick, and in their crushed state they rarely exhibit the posterior fringe of denticles. Careful examination of mauy specimens, however, shows that they precisely resemble those of Gonorhynchus. A detached scale from the hinder end of the caudal region is represented of the natural size in Pl. XVIII. fig. 4. The radiating grooves in its deeply overlapped portion are distinct, and the hinder fringe is partly restored from an adjoining scale. 3. NOTOGONEUS CUVIEEI. (?) 1818. Anormurus macrolepidotus, H. D. de Blainville, Nouv. Diet, d'Hist. Nat. vol. xxvii. p. 374. 1822. "Cyprin," G. Cuvier, Oss. Foss. ed. 2, p. 346, pl. lxxvii. fig. 15. 1844. Sphenolepis cuvieri, L. Agassiz, Poiss. Foss. vol. v. pt. i. p. 13, pt, ii. p. 39, pl. xliv, figs, 1, 2 (? figs. 4-12, nee fig. 3). |
