﻿Class — PISCES. 

 Order— GANOIDEI. 



Svb-okvkk—ACIjPENSEIWIDEI (see p. 8). 

 Family— PALiEONISCIDiE. 



Lepidoidei heterocerci, Agassis. 

 Sauroidei (pars), Ayassiz. 

 Acanthodei (pars), Agassiz. 

 Heterocerci monopterygii (pars), Giebel. 



Pal/eoniscidte (pars), Vogt. 

 Lepidosteides (pars), Pictet. 

 Lepidosteini heterocerci, Liitken. 

 Pal^oniscid,e, Martin. 



The body is fusiform, clothed with rhombic ganoid scales ; the paired fins are non- 

 lobate, the ventrals abdominal ; there is one dorsal fin, with short base of attachment, 

 and one anal ; the caudal is completely heterocercal and deeply cleft. The external head 

 bones are ganoid and usually sculptured ; the orbit is placed far forwards; the snout forms 

 a prominence over the front of the mouth. The suspensorium is oblique, the gape 

 correspondingly wide, the palatal arch and the jaws elongated ; the praeoperculum covers 

 a portion of the cheek above the maxilla, which is large and broad posteriorly. The 

 branchiostegal rays form a series of narrow flat imbricating ganoid plates. The notochord 

 is persistent ; there are apparently no ribs ; the vertebral arches, spinous processes, and 

 interspinous bones are ossified ; two sets of interspinous bones support at least the dorsal 

 fin. The shoulder-girdle displays well-developed infra-clavicular plates. The rays of all 

 the fins are numerous, closely set, and, save in the principal rays of the pectoral of some 

 genera, closely jointed ; those of the azygous fins overlap with their proximal extremities 

 their supporting ossicles, than which they are also more numerous. The anterior margin 

 of all the fins are in most, if not in all, cases set with fulcral scales, which probably 

 form a double series. The teeth are conical or cylindrical, very rarely plicate at the base, 

 with large internal pulp cavity and with a distinct enamel cap on the apex. 



The following genera are included in this family, an * being prefixed to the names of 

 those which have as yet occurred in British Carboniferous rocks. 



1. Cheirolejjis, Agassiz . . . Old Red Sandstone. 



2. Bhabdolepis, Troschel . . . Permian. 



*3. CosmqptycMus, Traquair . . Carboniferous. 



4. Palceoniscus, Blainville . . . Permian. 

 *5. Elonichtliys, Giebel . . . Carboniferous. 



