AMIID^. — ^CXll. 389 



[The Ganoid Irishes.) 



Skeleton bony or cartilaginous ; tail more or less 

 heterocercal; optic nerves forming a chiasma; arterial 

 bulb rhythmically contractile, 23rovided with several rows 

 of valves; air bladder frequently cellular and lung-like; 

 skin usually with bony plates; intestine usually with a 

 spiral valve; ventral fins, if present, abdominal. Of this 

 important sub-class but few species are now existing, 

 and these few vary widely from one another. Of the 

 earlier fossil fishes, a very large proportion are Ganoids. 



ORDEE OO.-OYCLOGANOIDEI. 



(The Gydogcmoids.) 



This order contains but a single species among recent 

 fishes. 



FAMILY CXII.— AMIIDvE. 



{The Bow-Fim.) 



Body oblong, rather stout, covered with thick cycloid 

 scales; tail heterocercal, the caudal jjeduncle curved 

 upwards behind, "like a sled-runner;" a large bony 

 buckler between branches of lower jaw; membrane 

 bones of head much developed, very hard; jaws broad, 

 with strong teeth in two sets, similar teeth on vomer, 

 palate and pterygoids; snout short, rounded; ventrals 

 large, abdominal; dorsal very long, the ravs of nearly 



