ORDER GANOIDEI. 



965 



compares the armour of the Coccosteans to that of the Siluroid 

 Teleosteans ; while Newberry and Pander compare the ventral 

 armour with the plastron of the Chelonia and Labyrinthodontia, with 



S*^^V^> 



Fig. 896. —Approximate restoration of the right lateral aspect of Coccosteus decipiens. Here the 

 ethmoids and orbits are introduced, but the skull and mouth are made too long. 



which, however, they also compare the true pectoral girdle of the 

 Sauropterygia. The nature of the dentition is unknown. 



Family Dinichthyid^e. — The genus Dinichthys, from the De- 

 vonian (Huronian) of North America, may probably be regarded as 

 forming the type of a family allied to the preceding. In this genus, 

 of which the type species has an estimated length of from 15 to 18 

 feet, the dentition (fig. 897) is remarkably like that of the Dipnoid 



Fig. 897. — Diagrammatic anterior aspect of the jaws of Dinichthys Hertzeri; from the 

 Devonian of North America. One-twelfth natural size. (After Newberry.) 



genus Protopterus, from which Dr Traquair concludes that there 

 was probably a close connection between the present group and the 

 Dipnoi. Other gigantic forms more and less closely allied to the 

 type genus are Titanichthys, Liognathus, and Diplognathus, from the 

 Devonian of Ohio ; while Typodus, from the same formation in the 

 Eifel, may perhaps belong to this family. 



As Placodermata, of which the serial position is uncertain, may 

 be mentioned Menaspis, from the Permian of Germany ; Acanth- 

 aspis, Acantholepis, and Asptdickthys, from the Devonian of Ohio ; 

 Pnigeacanthus and Lecracanthus, from the Carboniferous of Iowa; 

 Stichacanthus and Phoder acanthus, from the corresponding forma- 

 tion of Ireland and Belgium ; and Anomalichthys, from the Devonian 

 of Germany. 



Suborder 3. Acanthodea. — The last group of the Proganoids 

 is also Palaeozoic, and ranges from the Devonian to the Permian, 

 although it is not improbable that some of the genera, founded upon 

 fin-spines, which are noticed under the Elasmobranchei, should be 



