434 
ACTIXOPTERYGII. 
The so-called Platax (?) colchicus from the Lower Tertiary of the 
Caucasus (Simonovich, Batzevich, and Sorokin, Material. Geol. 
Kavkaza, 1875, p. 162, pis. i.-iii.) does not belong to this genus, 
and cannot be satisfactorily determined from the published 
description and figure. 
Genus AMPHISTIUM, Agassiz. 
[Poiss. Foss. vol. v. pt. i. 1844, p. 44.] 
Trunk much deepened, and head short and deep, with rather 
large supraoccipital crest. Eye large ; cleft of mouth of moderate 
size and directed upwards; teeth minute or absent. Paired fins 
small, the pelvic pair inserted in advance of the pectorals ; dorsal 
fin not much elevated, extending along the greater part of the back, 
with 3 or 4 feeble anterior spines; anal fin almost or quite as much 
extended as the dorsal, with 3 or 4 feeble anterior spines ; caudal 
fin rounded. Scales very small, none enlarged or thickened. 
Amphistium paradoxum, Agassiz. 
1796. Pleuronectes platesm, G. S. Volta, Ittialit. Veronese, p. clxxix. 
pi. xliv. fig. 1 (errore). 
1818. Pleuronectes platessa, H. D. de Blainville, Nouv. Diet. dTIist. 
Nat. vol. xxvii. p. 357 (errore). 
1835. Amphistium paradoxum, L. Agassiz, Neues Jahrb. p. 294 (name 
only). 
1834-44. Amphistium paradoxum, L. Agassiz, Poiss. Foss, vol, v. pt, i. 
p. 44, pi. xiii. 
Type. Nearly complete fish; Museum of Natural History, Paris. 
The ty])e species, attaining a length of about 0-2. Length of 
head with opercular apparatus somewhat exceeding half the 
maximum depth of the trunk, which is contained twice or slightly 
less in the total length to the base of the caudal fin. Dorsal and 
anal fins gently rounded and equally elevated, each with from 21 to 
23 stout, articulated and divided rays. 
Form. Loc. Upper Eocene : Monte Bolca, near Verona; Mont¬ 
martre, near Paris. 
?. 1982. Fine large specimen, wanting extremity of caudal fin ; 
Monte Bolca. The articulation of the mandible is beneath 
the orbit, and the upturned mouth bears traces of minute 
teeth. The operculum is quite smooth. The caudal 
portion of the vertebral column is nearly straight, but the 
very short abdominal portion curves sharply upwards. 
