556 
actinopterygii. 
by the extinct genus Odonteus with the following species, of which 
there are no remains in tho Collection : — 
Odonteus pygmcms, A. deZigno, Mem. It. Istit. Vencto, vol. xviii. 
(1874), p. 291, pi. x. tig. 1-; F. Bassani, Palseont. Italics, 
vol. iii. (1898), p. 83, pi. ix. tig. 5. — Upper Eocene ; Monte 
Bolca, near Verona. [Imperfect fish; Zigno Coll., Uni- 
versity of Padua.] 
Odonteus sparoides , L. Agassiz, Poiss. Foss. vol. iv. (1839), p. 1 ‘ 
pi. xxxix. fig. 2; F. Bassani, Atti Soc. Veneto-Trent. 
Sci. Nat. vol. iii. (1876), p. 176. Odonteus sparoides, var. 
depressus, F. Bassani, Palieont. Italica, vol. iii. (1898), 
p. 83, pi. viii. fig. 2. — Ibid. [The type species. Imper- 
fect fish ; Paris Museum of Natural History.] 
Odonteus aft. sparoides, F. Bassani, Atti It. Accad. Sci. Ts apoli 
[2] vol. iii, (1889), no. 6, p. 94, pi. xiii. fig. 3. — Lower 
Miocene; Chiavon, Vicentin. [Imperfect fish; Piovcne 
Coll., Lonedo.] 
Division D. CH2ET0D0NTIF0RMES. 
As Perciformes, but brain-caso very short, and facial region of 
skull much produced, with terminal small mouth. Specialisation 
resulting in degeneration of fins and shortening of vertebral axis. 
Synopsis of Families represented by Extinct Genera or Species. 
I. Fins normal, the dorsal spines well-developed. 
Maxilla separate from premaxilla .... Cimctodontid® (p. 556). 
Maxilla fused with premaxilla Acronurid® (p. 562). 
II. Fins reduced, the dorsal spines rarely more than 3, usually absent 
(Plectognathi). 
Maxilla fused with premaxilla, but 
marginal teeth distinct Balistid® (p. 565). 
Maxilla fused with premaxilla, and no 
distinct marginal teeth Gymnodontid® (p. 570). 
Family CIIiETODONTIDiE. 
Trunk deepened, with scales more or less densely covering arti- 
culated portions of median fins. Maxilla separate from prcmaxilla ; 
teeth minute and clustered. Vertebrae 9 or 10 in abdominal, 13 oi 
14 in caudal region. Anal fin with 3 or 4 spines. Scales small or 
minute, more or less ctenoid. 
Carnivorous fishes chiefly occurring in tropical seas in the neigh- 
