CHAPTER V. 



PART III. 



FOSSIL FISHES OF THE CTENOID, CYCLOID, AND 

 PLACOID OKDERS. 



CTENOID ORDER; PEROA BERYX SMBRDIS MONTE BOLCA ICHTHYOLITES. 

 CYCLOID ORDER ; ENCHODUS SATJRODON HYPSODON CYPRINOIDS ESO- 

 CIDS HALICOIDS OSMEROIDS ACROGNATHUS - AULOLEPIS - MALLOTUS. 

 PLACOID ORDER ; CHIM^IROIDS SQUALID^E HYBODONS CESTRACIONS 

 PRISTIDES RAYS ICHTHYODORULITES GEOLOGICAL DISTRIBUTION OF FOS- 

 SIL FISHES GENERA OF ICHTHYOLITES DT. THE BRITISH MUSEUM. 



CTENOID ORDER. The fishes of this Order, of which the 

 Perch is the type, have imbricated laminated scales, the pos- 

 terior margins of which are round and finely pectinated j i. e. 

 divided into small teeth like a comb. 



The Otenoidians first appear in the cretaceous formation, those from 

 the slate of Glaris being the most ancient known ; certain species and 

 genera are abundant in the White Chalk of the south-east of England, 

 and of Germany ; and may have been collected from strata of the same 

 age in the Brazils. In the tertiary limestones of Monte Bolca there are 

 numerous Ctenoid Ichthyolites. 



Almost all the fishes of this order in the Cretaceous formation are of 

 extinct genera. One half of those from the eocene of Monte Bolca 

 are also of lost generic types ; whilst all the Ctenoids of the newer ter- 

 tiary deposits belong to existing genera. The fossil Ctenoids in the 

 British Museum comprise nearly thirty genera, belonging to eight fami- 

 lies ; a list of the whole is subjoined. I proceed to point out a few of 

 the most interesting specimens. 



PERCA. Wall-case C. (No. 17.) Of this typical genus of the Ctenoid 

 order, there is a beautiful example of Perca lepidota, from the lacus- 

 trine deposits of (Eningen (ante, p. 184). * 



1 These tables show the position of the principal Ichthyolites in Case C. 

 No. 17, 18. 



_ No. YL _ No. 18. 



Perca ((Eningen). Cyclopoma (from Monte Bolca). 



Beryx. | Gyrodus. Peiatis. | Serranus. 



Rhacolepis (Brazils). | Enoplosus. Myripristis. 



Lates. Labrax. 



