186 A JPYCNODONT FISH OF THE GENUS MESOt>ON. 



specific relationship of so imperfect a fossil, since the most 

 nearly allied forms are known merely by fragmentary specimens.* 

 The fish is not a young individual of Mesodon damoni, which 

 is already represented by jaws from the Portland Stone of 

 Portland, f because in the immature state of this species (see 

 the narrow end of the dentition shown in PL B, Fig. 5), the 

 splenial teeth are less crowded than in the new fossil, while the 

 principal teeth are rounder. Nor can the specimen be referred 

 to the typical Mesodon macropterus (see Text-fig, below), or 

 Jlf. daviesi,% which are known by nearly complete fishes from the 

 Bavarian lithographic stone and the English Purbeck Beds re- 

 spectively, because in these species there is no sudden elevation 



Mesodon macropterus (Agassi/) ; left side view of fish, about one-half natural 

 size. Lithographic Stone; Bavaria, fr., frontal; m.eth., mesethmoid ; md., 

 mandible; op., operculum ; orb., orbit; p.op., preoperculum ; pa., parietal; 

 pnix., premaxilla ; s.occ., supraoccipital ; sq., squamosal ; v. vomer. 



* For an account of all known species of Mesodon see Catal. Foss. Fishes Brit. 

 Mus., Ft. III. (1895), pp. 199-215. 



t A. S. Woodward, " On a New Species of Pycnodont Fish (Mesodon damoni) 

 from the Portland Oolite," Geol. Mag. [3], Vol. VII. (1890), p. 158. 



% A. S. Woodward, " On some New Fishes from the English Wealden and 

 Purbeck Beds," Proc. Zool. Soc., 1890, p. 351, pi. xxviii., fig. 5. 



