Actinopterygii Aellieospondyli. 



107 



mouth and conical teeth. The thick-scaled Eugnathus (Fig. 151) 

 and the thin-scaled Caturus (Fig. 152) both range throughout 

 the Jurassic, the specimens from the Lower Lias of Lyme 



Wall-case, 

 No. 13, and 

 Table-case, 

 No. 44. 



FIG. 152. Co.turusfiircatv.it, Ag. : Lithographic Stone, Eavaria. [Scales omitted. 



Regis and the Lithographic Stone of Bavaria being particularly 

 fine. Neorlionibolepis is an interesting fish from the English 

 Chalk and Wealden, with rhombic enamelled scales and disc- 

 shaped vertebra?. 



The Amiidas are first certainly represented in the Upper 

 Jurassic. Megalurus, from the Lithographic Stone of Bavaria 

 and France and from the English Purbeck Beds, is very similar 

 to Amia but has a shorter dorsal fin. The existing genus is 

 represented by fine specimens from the Lower Miocene of 

 France, and is also known in Germany. Detached vertebrae 

 are shown from the Lower Tertiaries of the Hampshire Basin. 



A family of Amioids which curiously mimic the modern Wall-cases, 

 sword-fishes, ranges throughout the Jurassic and Cretaceous Table-case' 

 periods, and is represented by Pachycormus (Upper Lias), No. 45. 

 Hypsocormus (Oxfortlian and Kimmericlgian), and Protospliyrcena 

 (Upper Cretaceous), besides other genera. The notochord 

 is persistent, but to strengthen the trunk the vertebral arches 

 are multiplied and very closely arranged ; the powerful forked 

 tail is supported by a triangular expansion of one of the haemal 

 bones ; and the snout gradually becomes elongated until it is 

 a formidable weapon in Protosphyrcena. 



SUB-ORDER III. Aetheospondyli. 



Next to the Pachy conn i das, in an uncertain position, are Wall-case, 

 placed the Aspidorhynchidae and the modern Lepidosteidae, the No. 14, and 

 former ranging from the Lower Oolites to the Upper Chalk, the 

 latter exclusively Tertiary. AspidorJiyncJins (Fig. 153), with 

 prominent rostrum, is represented by a fine series of specimens 

 from the Lithographic Stone of Bavaria; the closely-related 

 Belonostomus, with elongated jaws but little or no prominent 

 rostrum, is shown both from this formation and in a unique 



