SUB-CLASS V 



GAXOIDEI 



89 



maxillae. The oldest known species is A. crassus, Sin. Wood., from the 

 Stonesfield Slate (Bathonian) of Oxfordshire. Well-preserved fishes in the 

 Lithographic Stone of Bavaria (A. acutirostris, Blv. sp.) and France; also in 

 the English Purbeck Beds (A. fisher i, Egerton). 



Belonostomus, Ag. As above, but mandible almost as long as the snout. 

 Kimmeridgian to Upper Cretaceous. Fine skeletons in the Lithographic 



DTTld 



Fig. 161. 



Aspidorhynchus acutirostris, Ag. Upper Jurassic ; Solenhofen. iop, Interoperculuni ; md, Mandible; mx, 

 Maxilla; op, Operculum; pmd, Predentary ; pop, Preoperculum ; pt, Pterygoid; qy,, Quadrate; ;■;, Hinder 

 cheek-plate ; so, Suborbitals ; sop, Suboperculum. 



Stone of Bavaria (B. split/ raenoides, Ag., etc.) and the Cretaceous of Europe, 

 India, Brazil, and Queensland. 



Family 8. Lepidosteidae. Bony pikes. 1 



Trunk elongated, with thick, enamelled rhombic scales. Snout much produced, the 

 very long maxilla divided by a series of vertical sutures into several pieces, which bear 

 large pointed laniary teeth and small clustered teeth ; premaxilla short and toothed. 

 Vomer double. Vertebral column completely ossified, bent upwards into the superior lobe 

 of the tail; vertebrae opisthocoelous. All fins with biserial fulcra. Dorsal and anal fins 

 very remote, near the hemi-heterocercal, rounded caudal fin. Tertiary and Recent. 



Lepidosteus, the only genus of this family, survives in the rivers of the 

 southern United States, Central America, and Cuba. Complete individuals 

 occur also in the Eocene and Lower Miocene of Europe and North America. 

 L. atrox, Leidy, from the Middle Eocene Green River Shales of Wyoming, 

 attains a length of 1*7 m. 



Order 5. AMIOIDEI. Liitken. 



Notochord persistent, or vertebrae in various degrees of ossification. Opercular 

 apparatus always complete, with larnelliform branchiostegal rays and a welldereloped 

 gular plate. Teeth pointed or conical. No infraclavicle. Fulcra present or absent. 

 Supports of dorsal and anal fins equal in number to the dermal rays. Caudal fin hemi- 

 heterocercal. Scales very thin, overlapping, rounded or rhombic at the hinder border. 



The Amioids are distinguished from the Lepidostei by their thin, cycloid 

 or rhombic scales, which are not articulated with each other, but merely 



1 Eastman, C. R., Fossil Lepidosteids from the Green River Shales of Wyoming (Bull. Mus. 

 Comp. Zool. vol. XXXVI. p. 67), 1900. Also Geol. Mag. [4] vol. VII. p. 54, 1900. 



