PAL^ORHYNCHID^. 
483 
neural and haemal spines with a thin laminar expansion on the 
hinder border. Pectoral fins small; pelvic fins large; dorsal and 
anal fins much extended, the greater part consisting of feeble 
spines ; caudal fin distinct and well developed. Scales thin and 
cycloid, or absent. 
An imperfectly known extinct family, inhabiting the seas of the 
Eocene, Oligocene, and Miocene periods. The precise constitution 
of the cranial rostrum is undetermined. 
Synopsis of Genera. 
Jaws of equal length ; dorsal fin-spines as 
numerous as vertebrae below them. Palcsorhynchus (p. 483).. 
Mandible about half as long as rostrum; dorsal 
fin-spines much more numerous than ver¬ 
tebrae below them... Hemirhynchtis (p. 488). 
Genus PAL-ffiaRHYNCHUS, H. D. de Blainville. 
[Jn’ouv. Diet. d'Hist. Nat. vol. xxvii. 1818, p. 3^14.] 
Articulation of mandible beneath anterior border of orbit, and 
slender jaws nearly of equal length; teeth apparently absent; 
preoperculum large and triangular, ornamented with numerous 
radiating grooves ; operculum quadrangular. Vertebrae about 25 
in the abdominal, 35 in the caudal region. Pectoral fins small and 
delicate ; pelvic fins large, directly beneath the pectorals, each with 
6 rays ; dorsal fin extending almost the whole length of the back, 
its spines consisting of imperfectly-fused right and left halves, and 
as numerous as the vertebrae below them ; anal fin also very ex¬ 
tensive, the greater part co-nsisting of spines resembling those of the 
dorsal; caudal fin forked. Dorsal and anal fin-spines supported by 
small fan-shaped bones, which are strengthened by three radiating 
ribs, the shortest extending along the margin of the trunk, the 
others diverging towards the vertebral axis. Scales small and 
ovoid. 
Falseorhynchus glarisianus^ Blainville. 
[Text-figure 17.] 
1716. Figure by J. J. Scheuchzer, Mus. diluvianum, pi. ix. fig. 6. 
1818. PalcBorhynchmn glarisianum, H. D. de Blainville, Nouv. Diet. 
d’Hist. Nat. vol. xxvii. p. 314. 
1834. Palceorhynchum glarisianum, L. Agassiz, Neues Jahrb. p. 303. 
1842-44. Palceorhynchum glarisianum, L. Agassiz, Poiss. Foss. vol. v, 
pt. i. p. 81, pi. xxxiv. 
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