AMIID^E. CXH. 305 



The Ganoid Fishes. 



Skeleton bony or cartilaginous; tail more or less 

 heterocercal; optic nerves forming a chiasma; arterial 

 bulb rhythmically contractile, provided 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. 



OEDEE OO.-OTOLOGAE OIDEI. 



(The Cydoganoids.) 



This order contains but a single species among recent 

 fishes. 



FAMILY CXIL AMIID^E. 



(The Bow -Fins.) 



Body oblong, rather stout, covered with thick cycloid 

 scales; tail heterocercal, the caudal peduncle curved 

 upwards behind, &quot;like a sled -runner;&quot; 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 rays of nearly 

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