464 
ACTIN-OPTERTGII. 
constricted, with one lateral pit; base of haemal arches in hinder 
abdominal region a small trellis-work. Pectoral and pelvic fins 
small; dorsal fins widely separated, the anterior consisting of 10 to 
16 spines, most of which are clasped by the enlarged U-shaped upper 
end of a shortened support ^; posterior dorsal and anal fins small, 
similar, and opposite, followed by 5 to 8 detached finlets ; caudal fin 
deeply forked. Small scales only on anterior part of trunk, those of 
pectoral region somewhat enlarged and compacted. 
One existing species in Atlantic, Mediterranean, and Indian 
Oceans. 
Auxis (?) propterygius (Agassiz). 
1796. Sco7nher pelamis, G. S. Volta, Ittiolit. Veronese, p. Ixvi. pi. xiv« 
fig. 2 [errore). 
1796. Scomber trachurus, G. S. Volta, ibid. p. cxxv. pi. xxix. fig. 2 
[eii'ore). 
1796. Opliicephalus striatus, G. S. Volta, ibid. p. cxciii. pi. xlviii. fig. 1 
{err ore). 
1796. Labrus bifasciatus, G. S. Volta, ibid. p. cciv. pi. 1. fig. 1 {errore). 
1818. Scomber pelamis (?), H. D. de Blainville, Noiiv. Diet. d’Hist. Nat, 
vol. xxvii. p. 345. 
1818. Scomber trachurus, H. D. de Blainville, ibid. p. 345. 
1818. Labrus bifasciatus (“ ? une des especes de scombres ”), H. D. de 
Blainville, ibid. p. 351. 
1835. Tliynnus propterygius, L. Agassiz, Neues Jahrb. p. 292 (name 
only). 
1835-44. Tliynnus propterygius, L. Agassiz, Poiss. Foss. vol. v. pt. i. 
p. 55, pi. xxvii. 
1876. Tliynnus propterygius, F. Bassani, Atti Soc. Veneto-Trent. Sci. 
Nat. vol. hi. p. 183. 
1882. Thynnus propterygius (? = Auxis), D. G. Kramberger, Beitr. 
Palaont. Oesterr.-Ungarus, vol. ii. p. 118. 
Type. Imperfect fish ; Museum of Natural History, Paris. 
An imperfectly known species attaining a length of about 0*25. 
Length of head with opercular apparatus contained about three and 
a third times, maximum depth of trunk approximately five times 
in the total length of the fish to the base of the caudal fin. Vertebrae 
30 in total number. Posterior dorsal and anal fins with about 12 
articulated rays, followed by 7 finlets. 
Form. Log. Upper Eocene : Monte Bolca, near Verona. 
P. 4137. Small specimen 0*1 in length, probably young of this 
species. The enlarged scales in the pectoral region are 
^ See Kramberger, Beitr, Palaont. Oesterr.-TJngarns, vol. ii. (1882), p. 117, 
fig. 1. ^ ,, V 
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