ORDER GANOIDEI. 



973 



usually large, and completely diphycercal ; the swim-bladder is 

 ossified, and the scales are cycloidal. The members of this family 

 are further characterised by the full development of the cranial 

 bones ; and the arrangement of the ossifications in the orbit ap- 



Fig. 909. — Skeleton of Undina fienicillata ; from the Kimeridgian of Bavaria, one-fourth 

 natural size, a, Jugular plates ; b, Swim-bladder ; c, Pelvis. 



proaches that found in the Labyrinthodontia. The type genus 

 Ccelacanthus ranges from the Carboniferous of Europe and North 

 America to the Upper Trias of the former area, and is well charac- 

 terised by the great thickness of its scales. 



More or less nearly allied are Diplurus from the Trias of New 



Fig. 910.— Skeleton of Macropoma Mantelli ', from the Chalk of Sussex. Reduced. 

 Letters as in fig. 909. (After Huxley.) 



Jersey, Graphiurus from the Upper Trias of Carniola, and Hepta- 

 nema ranging from the Middle Trias to the Upper Jurassic of the 

 Continent. In Undina (fig. 909) the exposed parts of the scales 

 are marked by ridges, rising in some parts into spines, and the 



