12 ANATOMY OF VERTEBRATES. 



Order VII. LOPHOBRAXCIIII. 



Endoskeleton partially ossified, without ribs ; exoskeleton ganoid ; 

 gills tufted ; opercular aperture small ; swim-bladder without air- 

 duct. Males marsupial. 



Fam. 1. HippocampidcB. Ex. Sea-horse. 

 2. Syngnathidcs. Ex. Pipe-fish. 



B. Arterial bulb muscular, with more than one row of valves. 

 Optic nerves not decussating. 



Order VIII. GAXOIDEI. 



Endoskeleton cartilaginous, partly bony, or ossified ; in a few 

 recent and in most palaeozoic extinct forms, notochordal ; exo- 

 skeleton as ganoid scales or plates ; fins usually with the first 

 ray a strong spine ; caudal fin in most unsymmetrical ; a swim- 

 bladder, often cellular, and with an air-duct ; intestine in many 

 with a spiral valve. 



Suborder I. Lepidoganoidei. 



Fain. 1. Salamandroidei. Ex. Lepidosteus, Polypterus. 



2. Pycnodontidce. Ex. Pycnodus. 



3. Lepidoidei. Ex. Dapedius. 



4. LeptoIepidcB. Ex. Leptolepis. 



5. Acanthodei. Ex. Acanthodes. 



6. DipteridcB. Ex. Dipterus. 



7. Coelacanthi. Ex. Ccelacanthus. 



8. Holojjtychidce. Ex. Holoptychius. 



Suborder II. Placogaxoidei. 



Fam. 1. SturionidcE. Ex. Sturgeon. 



2. Ostracostei. Ex. Pterichthys. 



Subclass III. Order IX. HOLOCEPHALI. 



Endoskeleton cartilaginous, subnotochordal ; cranial wall com- 

 plete ; tympanic pedicle confluent therewith ; endoskeleton as 

 plaeoid granules. Anterior dorsal fin with a strong spine; 

 mouth terminal, beak- shaped; dental plates and columns fused 

 with the jaws. Optic nerves not decussating. Valves of bulbus 

 arteriosus multiserial. Gills laminar, with a small proportion of 



