108 



PISCES. 



Amia; and some of the small tooth-like gill-rakers are arranged on the 

 edge of little triangular flakes of bone exactly like those of the recent 

 genus. A few of the diamond-shaped thick scales persist on the atrophied 

 upper caudal lobe. The typical species of Caturus (C. furcatus) occurs in 

 the Lithographic Stone (Lower Kimmeridgian) of Bavaria, arid several 

 others are found in the Upper Jurassic ; but the genus appears to have an 

 even wider range than Eugnalhus, the earliest species being found in the 

 RhfBtic or Upper Triassic of Seefeld in the Tyrol, while fragments appa- 

 rently to be placed here occur in the English Purbeck Beds, perhaps even 

 in the Wealden. 



FIG. 77. 



Eurycormus sjwciosus ; foremost abdominal vertebrae (A), posterior abdominal 

 vertebrae (B), and caudal vertebra? (c), somewhat reduced. U. Jurassic 

 (Lithographic Stone); Bavaria, h, haemal arches; he., hypocentra ; n, 

 neural arches; pi., pleurocentra. 



Eurycormus (fig. 77). Intermediate between Caturus and Amia. The 

 notochord is persistent, but the ossifications in the notochordal sheath are 

 robust, and the pleurocentra and hypocentra form alternating completed 

 rings in the caudal region (fig. 77 c). Fulcra are comparatively small on 

 the median fins, unknown on the paired fins. The anal fin is considerably 

 extended, and the caudal fin deeply forked. The typical species is E. 

 spedosus from the Bavarian Lithographic Stone, while more fragmentary 

 though characteristic specimens are known from the Oxford and Kim- 

 meridge Clays of England. 



While the Eugnathidse thus closely approach the Amiidse 

 in the Jurassic period, there is fragmentary evidence of other 

 interesting modifications in the Cretaceous. Neorhombolepis 

 (English Chalk and Wealden) and Otomitla (Neocomian of 

 Mexico) have completely ossified vertebras but retain the 

 rhombic squamation of EiLgnathus, while the Mexican fish also 

 appears to exhibit a subdivision of the gular plate. Lophiosto- 

 mus (English Chalk and Cambridge Greensand) has similar 

 scales, and a pair of prominences on the hinder half of the roof 

 of the skull. 



