5o6 FOSSIL ACANTHOPTERYGIAN FISHES. 



The hake Merluccius, and fishes allied to the cod, are found in the 

 London Clay. Paloeogadus and like forms occur in the schists of 

 Glarus. The Pleuronectidse are carnivorous fishes, dating from the 

 Tertiary period. A species of turbot, Rhombus, is found at Monte 

 Bolca, and soles occur near Ulm. 



The Physostomi comprises fishes with all the fin rays jointed, 

 though the first rays of the dorsal and pectoral fins are sometimes 

 ossified ; it includes thirty-one families. The Siluroid fishes cer- 

 tainly date from the Cretaceous period, though they become charac- 

 teristic of the Tertiary rocks. The deep-sea Scopelidae are represented 

 by the so-called Osmeroides from Lebanon, and other genera allied to 

 Saurus from Comen in Istria and the Middle Tertiary of Licata in 

 Sicily. The Carps appear in the Middle Tertiary deposits of (Eningen 

 and the Lignites of Bonn and Bilin, and are mostly referable to exist- 

 ing genera, Cyprinus, Tincta, Leuciscus, Rhodeus, Cobitis. Cyprinodon 

 is found at Aix in Provence and the Middle Tertiary of Germany. 

 The Scombresocidse are represented at Monte Bolca by ffolosteus, and 

 in some Middle Tertiary beds by the gar pike, Belone. The true pike, 

 Esox, dates from the (Eningen beds. The Osmeroides of the Chalk 

 is allied to the smelt, and is associated with Aulolepis, Tomognathus, 

 and Acrognathus, which probably belong to the salmon family. 



The herrings are represented in the Gault by ThrissopaUr ; in the 

 Chalk by Opisthopteryx, while Clupea, Engraulis the anchovy, and 

 Chanos of the Indian seas are found in the Lower Tertiary associated 

 with many extinct genera. The Hoplopleuridas is an extinct family, 

 first known in the Chalk, and extending into the Tertiary, represented 

 by Saurorhamphus, Pelargorhynckus, <fec. Finally, the Eels are 

 represented in the London Clay by Khynchorkinus, and in the Monte 

 Balca beds occur the living Anguilla, and the tropical Ophichthys. 



The Lophobranchiate order is represented by the Tertiary genus 

 Solenorhynckus, the true pipe fish Syngnathus, and the sea-horse 

 Calamastoma, found at Monte Bolca. 



The order Plectognathi comprises fishes with rough scales, or 

 spiny ossifications in the skin, and few imperfectly ossified vertebrae. 

 The Scleroderm family is represented by Glyptocephalus of Sheppey, 

 which resembles the living file-fish, Batistes ; the box-fish, Ostracion, 

 occurs at Monte Bolca ; and the schists of Glarus yield Acanthoderma 

 and Acanthopleurus. The Gymnodonts are represented in a fossil state 

 by a Diodon at Monte Bolca, Enneodon from Monte Postale, and 

 Trigonodon from the Middle Tertiary of Turin. 1 



If the Lampreys occur in a fossil state, they are only known from 

 their dental plates. Organs which closely resemble the teeth of living 

 Cyclostomata are frequently met with in the Cambrian, Silurian, and 

 Devonian rocks, and are known as Conodonts. 



Amphibia. The amphibia are a group which exemplify the evo- 

 lution of animals in the circumstance that they begin life as fishes, 



1 See Pictet : "Traite de Paleontologie," Tom. II., Gunther's "Study of Fishes, " 

 and monographs by E. Ray Lankester, and by Traquair, in Palseontographical 

 Society's Publications. 



