PAL.a50RHTXCHID.3E. 
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 vertebra below them PaUeorhynchus (p. 483). 
Mandible about half as long as rostrum ; dorsal 
fin-spines much more numerous than ver- 
tebra below them Eemirhynchus (p. 488). 
Genus PALffiORHYNCHUS, H. D. de Blainville. 
[Nouv. 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. Vertebra about 2o 
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 vertebra below them ; anal fin also veiy cx 
tensive, the greater part consisting of spines resembling those of the 
dorsal ; caudal fin forked. Dorsal and anal fin-spines supported by 
email fan-shaped bones, which are strengthened by three radiatin D 
ribs, the shortest extending along the margin of the trunk, the 
others diverging towards the vertebral axis. Scales small au 
ovoid. 
Palaeorhyncbus glarisianus, Blainville. 
[Text-figure 17.] 
1716. Figure bv J. J. Scheuchzer, Mus. diluvianum, pi. ix. fig. 6. 
1818. PaUeorhynchum ylarisianum, H. D. de Blainville, Nouv. Diet. 
d’Hist. Nat. vol. xxvii. p. 314. 
1834. PaUeorhynchum ylarisianum , L. Agassiz, ISeues Jahrb. p. o03. 
1842-44. PaUeorhynchum ylarisianum } L. Agassiz, 1 oiss. I 1 oss. vol. v. 
pt. i. p. 81, pi. xxxiv. 
