CHIEOCENTRIDJE. 
89 
47514 . Type specimen, comprising left dentary and impression of 
left maxilla. The extent of the mandibular dentition, 
which comprises 23 teeth, is 0’04o. 
Presented hy Herr P. D. Ji. Yerheele, 1876, 
Genus PLATINX, Agassiz. 
[Xeues Jahrb. 1835, p. 304."] 
Syn. Thrissopierus, J. J. Heckel, Deukschr. k. Akad. Wiss., math.- 
naturw. Cl. Yol. xi. 1856, p. 245. 
Trunk elongated and laterally compressed; abdomen trenchant. 
Teeth small and in regular close series in both jaws, not enlarged in 
the premaxilla. About six or seven branchiostegal rays. Tertebrae 
approximately 70 in number, nearly half being caudal; ribs round 
in section. Pectoral fins considerably enlarged, the length of the 
rays exceeding that of the head with opercular apparatus ; pelvic 
fins very small: dorsal fin low and much extended, opposed to the 
anal, which is also much extended but not elevated into a pointed 
lobe in front; caudal fin deeply forked. Scales large and smooth. 
The following species of this extinct genus are recognised, but are 
not represented in the Collection : — 
Platinx catullii : Tlirissopterus catuUii^ J. J. Heckel, Henkschr. k. 
Akad. AYiss,, math.-natnrw. Cl. vol. xi. (1856), p. 248, 
pi. xii. fig. 5.—Upper Eocene ; Monte Bolca, near Verona. 
[The type species of Tlirissojpterus. Xearly complete fish ; 
University Museum, Padua.] 
Platinx elongatus, L. Agassiz, Xeues Jahrb. 1835, p. 304, and 
Poiss. Eoss. vol. V. pt. ii. (1835-44), p. 125, pi. xiv. ; 
E. Bassani, Atti Soc. Yeneto-Trent. Sci. Vat. vol. iii. 
(1876), p. 1^8. Hsox macrop)terus, H. D. de Blaiuville, 
Xoiiv. Diet. d'Hist. Xat. vol. xxvii. (1818), p. 342.—Ibid. 
[The type species. Yearly complete fish ; Paris Museum 
of Xatural Histor\'.] ^ /,.n, 
Platinx gigcis, L. Agassiz, Xeues Jahrb. 1835, p. 304. ILonojpteros 
gigas, G. S. Volta, Ittiolit. Veronese (1796), p. exei, 
pi. xlvii.—Ibid. [Yearly complete fish; Paris Museum 
of Yatural History.] 
Genus CHIROMYSTUS, Cope. 
[Proc. Amer. Phil. Soc. vol. xxiii. 1886, p. 4.] 
Trunk elongated and laterally compressed. Teeth rounded in 
section and hollow, not in deep sockets but firmly fixed to the jaws ; 
